Viviendas productivas

El presente trabajo recoge los resultados de una investigación sobre la «vivienda productiva», es decir, de la casa como lugar de trabajo. Dicha investigación se ha ocupado de explorar cómo influyen las cotidianeidades doméstico-laborales actuales —junto con sus arquitecturas y los urbanismos que estas generan— en la sociedad, en especial en temas sociales centrales como la construcción de las subjetividades, y de una vida en comunidad. Asimismo, explora cómo podrían influir en un futuro. La hipótesis sobre la que se trabaja, y que finalmente se intenta demostrar, consiste en que, en la territorialidad múltiple de lo laboral, la vivienda, como plataforma doméstica multiusos, productiva y reproductiva de la que muchas personas disponen, desempeña un papel nodal, y es posible que en el futuro su papel sea aún más importante y más visible. La vivienda productiva funciona como una infraestructura urbana desde la cual se construyen diferentes tipos de bienes materiales e inmateriales, pero sobre todo formas de relación, sociales y productivas con otros, además de imaginarios y afectos. La vivienda como infraestructura productiva y reproductiva es tanto «fábrica fundamental de lo social», como nos enseña Silvia Federici, como «fábrica de lo urbano». El trabajo en casa, como parte de diferentes dinámicas «dispersas» del trabajo que se dan en la actualidad, presenta tanto problemáticas y desafíos importantes, como capitales y posibilidades sociales. Por un lado, puede facilitar una absorción de tipo «24/7» vinculada a las lógicas de producción dispersa y consumo dominantes además de la que se da por las dinámicas patriarcales tradicionales, y en múltiples casos situaciones de evidente asimetría y de explotación laboral. También puede propiciar situaciones socialmente extendidas o impuestas de soledad y aislamiento. Sin embargo, está asimismo vinculado al surgimiento de espacios de experimentación tanto en soledad como en compañía, de cooperación y de intercambio, además de a la evidente posibilidad de construir rutinas propias y, por tanto, una subjetividad laboral propia. Por otro lado, frente a la idea general y homogénea del trabajador casero como un sujeto mayoritariamente aislado de su entorno, las jornadas de trabajo de los trabajadores caseros estudiados presentan una gran diversidad. Estas pueden conllevar aislamiento y exclusión, así como acompañar diferentes formas de construcción de una ciudadanía activa, tanto en solitario, como mediante formas de participación activa en la construcción de una vida en comunidad. En esta investigación se analizan, pues, desafíos y oportunidades de estas espacialidades del trabajo y, a través de este análisis, se indaga en el papel de los marcos físicos, organizativos y simbólicos actuales para la vivienda y para la ciudad pensada desde los trabajadores caseros. Al mismo tiempo se exploran nuevos tipos de vivienda y urbanismos que puedan quizás acompañar procesos sociales de inclusión, así como de emancipación, cooperación e intercambio y, en general, nuevas formas de vecindad y bienestar compartido en los ámbitos doméstico-productivos. Metodológicamente, las singularidades presentes en las realidades estudiadas invitan además a explorar protocolos de análisis, métodos de diseño, de gestión y gobierno que, desde lo micro, puedan dialogar con lo cotidiano y sus singularidades. Diego Barajas, autor de la tesis, es arquitecto dedicado a la práctica, a la investigación y la docencia. Su trabajo se focaliza en explorar el carácter mediador de la arquitectura frente a lo cotidiano y sus microrrealidades. Es profesor de proyectos de urbanismo en la IE School of Architecture y es miembro de Husos, una plataforma de investigación y diseño orientada a la innovación en arquitectura y urbanismo, con sede en Madrid. Es el autor del libro Dispersion, A Study of Global Mobility and the Dynamics of a Fictional Urbanism (Episode Publishers, Róterdam, 2003). Sus trabajos teóricos y de investigación han aparecido en libros y revistas internacionales tales como The Domestic and The Foreign in Architecture (010 Publishers, 2008), Public Spheres, a Europan Discussion (Europan9, 2007), Photoespaña 05 (La Fábrica, Madrid, 2005), Domus, Volume, Abitare, Architese, Plot, y Summa+. Su trabajo se ha expuesto en la Bienal de Venecia (selección principal), la Bienal de Róterdam, la Fundación Tapies, Photoespaña, entre otros y es parte de la colección permanente del FRAC Centre en Orleans y del Historisch Museum de Róterdam entre otros. Antes de estudiar en Róterdam, se gradúa con Honores en la Universidad de los Andes en 1999 y su tesis de grado de arquitectura recibe la máxima distinción como proyecto de Grado Meritorio. ABSTRACT The present study records an investigation into the «productive house», or the home as a workplace. This investigation looks at how working from home, its architectures, and the urban dynamics generated around it influence daily life and the construction of society. It also explores what influences home-based work might have in the future, particularly in central themes such as the biopolitical construction of subjectivities and community life. The central hypothesis revolves around the idea that the home, as a multi-use infrastructure that most of us have access to, plays a fundamental role in the contemporary work sphere, due to —or even in spite of— the omnipresence of work in practically every moment and area of our daily lives, and might play a main role in the future. The home functions as a kind of hub from which we create different kinds of material and immaterial goods, but above all relationships with others, both social and productive, as well as imaginaries and affections. The home, as a machine for production and reproduction, is as much a main «factory of the social» as Silvia Federici describes it, as a «factory of the urban». Working from home, as one of several «dispersed» work dynamics that are part of the contemporary world of work, presents as many important problematics and challenges as it does possibilities and social capital. On the one hand, it can contribute to kind of «24/7» absorption linked both to the logistics of the current dispersed production and consumption, and to that of traditional patriarchal dynamics, and in some cases even clearly asymmetrical situations that exploit the workforce. It can also lead to the socially widespread phenomena of isolation and loneliness, at times imposed upon home-based workers. However, by the same token, it is also linked to the growth of experimental spaces of cooperation and exchange, both solitary and in company, as well as the clear possibility of constructing individualised routines and, therefore, a personal laboural subjectivity. On the other hand, contrary to the generalised, homogenous idea of a home-based worker who is mostly isolated from his or her environment, the working days of those we studied went hand in hand with different ways of building subjectivities. This could be as much in exclusion and isolation as through building an active citizenship, at times in solitary and at times actively participating in the construction of communal life. In this investigation, therefore, the challenges and opportunities of the home as workplace have been analysed, and through this analysis we have inquired into the role of current physical, organisational and symbolic frameworks for the home and for the city from the perspective of home workers. At the same time we have explored new types of homes and of town planning that could perhaps accompany social processes of diversity and inclusion as well as emancipation, cooperation and exchange and, in general, new forms of shared welfare in productive domestic environments. Methodologically, the singularities present in the cases studied also invite us to explore protocols of analysis, methods of design, management and government that, from the micro level, could dialogue with the peculiarities of day-to-day life. The author of this thesis, Diego Barajas, is an architect dedicated to practice, investigation and teaching. His work is focussed on exploring the mediating nature of architecture and the built environment in terms of daily life and its microrealities. He is professor of urban projects at the IE School of Architecture and member of Husos, a platform for investigation and town planning based in Madrid. He is the author of the book Dispersion, A Study of Global Mobility and the Dynamics of a Fictional Urbanism (Episode Publishers, Rotterdam, 2003) and his theoretical works and investigations have appeared in books such as The Domestic and The Foreign in Architecture (010 Publishers, 2008), Public Spheres, a Europan Discussion (Europan9, 2007), Photoespaña 05 (La Fábrica, Madrid, 2005), and in international magazines such as Domus, Volume, Abitare, Architese, Plot and Summa+. His work has been exhibited in places such as the Venice Biennial (main selection), the Rotterdam Biennial, the Tapies Foundation and Photoespaña, among others, and forms part of the permanent collection of the FRAC Centre in Orleans and the Historisch Museum of Rotterdam. Before studying in Rotterdam, he graduated with Honours from the University of the Andes in 1999, and his architecture degree thesis received the maximum distinction of Meritorious Graduation Project.

Attempted hydrogen–deuterium exchange of the protio-trimethyloxonium dication (CH3)3OH2+, study of methylating ability of (CH3)3O+ in superacids and theoretical investigations

Attempted hydrogen–deuterium exchange of trimethyloxonium ion, (CH3)3O+ with excess of 1:1 2HF/SbF5 superacid at −30°C over a period of 30 days showed no exchange. Theoretical calculations at the MP2/6–31G** level are in accord with the lack of hydrogen–deuterium exchange in the methyl group of the (CH3)3O+ cation as protonation (protosolvation) prefers the oxygen lone pair of electrons, instead of a C—H bond. Methylation of aromatics with the (CH3)3O+CF3SO3− in CF3SO3H and 2CF3SO3H:B(O3SCF3)3 was also studied. Whereas in triflic acid no alkylation was observed, in triflatoboric acid, a powerful superacid, alkylation takes place, indicating protolytic activation of the trimethyloxonium ion.

Brefeldin A-inhibited guanine nucleotide-exchange activity of Sec7 domain from yeast Sec7 with yeast and mammalian ADP ribosylation factors

The Saccharomyces cerevisiae Sec7 protein (ySec7p), which is an important component of the yeast secretory pathway, contains a sequence of ≈200 amino acids referred to as a Sec7 domain. Similar Sec7 domain sequences have been recognized in several guanine nucleotide-exchange proteins (GEPs) for ADP ribosylation factors (ARFs). ARFs are ≈20-kDa GTPases that regulate intracellular vesicular membrane trafficking and activate phospholipase D. GEPs activate ARFs by catalyzing the replacement of bound GDP with GTP. We, therefore, undertook to determine whether a Sec7 domain itself could catalyze nucleotide exchange on ARF and found that it exhibited brefeldin A (BFA)-inhibitable ARF GEP activity. BFA is known to inhibit ARF GEP activity in Golgi membranes, thereby causing reversible apparent dissolution of the Golgi complex in many cells. The His6-tagged Sec7 domain from ySec7p (rySec7d) synthesized in Escherichia coli enhanced binding of guanosine 5′-[γ-[35S]thio]triphosphate by recombinant yeast ARF1 (ryARF1) and ryARF2 but not by ryARF3. The effects of rySec7d on ryARF2 were inhibited by BFA in a concentration-dependent manner but not by inactive analogues of BFA (B-17, B-27, and B-36). rySec7d also promoted BFA-sensitive guanosine 5′-[γ-thio]triphosphate binding by nonmyristoylated recombinant human ARF1 (rhARF1), rhARF5, and rhARF6, although the effect on rhARF6 was very small. These results are consistent with the conclusion that the yeast Sec7 domain itself contains the elements necessary for ARF GEP activity and its inhibition by BFA.

Natural genetic exchange between Haemophilus and Neisseria: Intergeneric transfer of chromosomal genes between major human pathogens

Members of the bacterial families Haemophilus and Neisseria, important human pathogens that commonly colonize the nasopharynx, are naturally competent for DNA uptake from their environment. In each genus this process is discriminant in favor of its own and against foreign DNA through sequence specificity of DNA receptors. The Haemophilus DNA uptake apparatus binds a 29-bp oligonucleotide domain containing a highly conserved 9-bp core sequence, whereas the neisserial apparatus binds a 10-bp motif. Each motif (“uptake sequence”, US) is highly over-represented in the chromosome of the corresponding genus, particularly concentrated with core sequences in inverted pairs forming gene terminators. Two Haemophilus core USs were unexpectedly found forming the terminator of sodC in Neisseria meningitidis (meningococcus), and sequence analysis strongly suggests that this virulence gene, located next to IS1106, arose through horizontal transfer from Haemophilus. By using USs as search strings in a computer-based analysis of genome sequence, it was established that while USs of the “wrong” genus do not occur commonly in Neisseria or Haemophilus, where they do they are highly likely to flag domains of chromosomal DNA that have been transferred from Haemophilus. Three independent domains of Haemophilus-like DNA were found in the meningococcal chromosome, associated respectively with the virulence gene sodC, the bio gene cluster, and an unidentified orf. This report identifies intergenerically transferred DNA and its source in bacteria, and further identifies transformation with heterologous chromosomal DNA as a way of establishing potentially important chromosomal mosaicism in these pathogenic bacteria.

Molecular keys to speciation: DNA polymorphism and the control of genetic exchange in enterobacteria

Speciation involves the establishment of genetic barriers between closely related organisms. The extent of genetic recombination is a key determinant and a measure of genetic isolation. The results reported here reveal that genetic barriers can be established, eliminated, or modified by manipulating two systems which control genetic recombination, SOS and mismatch repair. The extent of genetic isolation between enterobacteria is a simple mathematical function of DNA sequence divergence. The function does not depend on hybrid DNA stability, but rather on the number of blocks of sequences identical in the two mating partners and sufficiently large to allow the initiation of recombination. Further, there is no obvious discontinuity in the function that could be used to define a level of divergence for distinguishing species.

Def1 Promotes the Degradation of Pol3 for Polymerase Exchange to Occur During DNA-Damage–Induced Mutagenesis in Saccharomyces cerevisiae

Funding: Wellcome Trust, 070247/Z/03/A. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Efficient exchange of the primary quinone acceptor QA in isolated reaction centers of Rhodopseudomonas viridis

A key step in the conversion of solar energy into chemical energy by photosynthetic reaction centers (RCs) occurs at the level of the two quinones, QA and QB, where electron transfer couples to proton transfer. A great deal of our understanding of the mechanisms of these coupled reactions relies on the seminal work of Okamura et al. [Okamura, M. Y., Isaacson, R. A., & Feher, G. (1975) Proc. Natl. Acad. Sci. USA 88, 3491–3495], who were able to extract with detergents the firmly bound ubiquinone QA from the RC of Rhodobacter sphaeroides and reconstitute the site with extraneous quinones. Up to now a comparable protocol was lacking for the RC of Rhodopseudomonas viridis despite the fact that its QA site, which contains 2-methyl-3-nonaprenyl-1,4-naphthoquinone (menaquinone-9), has provided the best x-ray structure available. Fourier transform infrared difference spectroscopy, together with the use of isotopically labeled quinones, can probe the interaction of QA with the RC protein. We establish that a simple incubation procedure of isolated RCs of Rp. viridis with an excess of extraneous quinone allows the menaquinone-9 in the QA site to be almost quantitatively replaced either by vitamin K1, a close analogue of menaquinone-9, or by ubiquinone. To our knowledge, this is the first report of quinone exchange in bacterial photosynthesis. The Fourier transform infrared data on the quinone and semiquinone vibrations show a close similarity in the bonding interactions of vitamin K1 with the protein at the QA site of Rp. viridis and Rb. sphaeroides, whereas for ubiquinone these interactions are significantly different. The results are interpreted in terms of slightly inequivalent quinone–protein interactions by comparison with the crystallographic data available for the QA site of the two RCs.

The signal recognition particle receptor of Escherichia coli (FtsY) has a nucleotide exchange factor built into the GTPase domain

Targeting of many secretory and membrane proteins to the inner membrane in Escherichia coli is achieved by the signal recognition particle (SRP) and its receptor (FtsY). In E. coli SRP consists of only one polypeptide (Ffh), and a 4.5S RNA. Ffh and FtsY each contain a conserved GTPase domain (G domain) with an α-helical domain on its N terminus (N domain). The nucleotide binding kinetics of the NG domain of the SRP receptor FtsY have been investigated, using different fluorescence techniques. Methods to describe the reaction kinetically are presented. The kinetics of interaction of FtsY with guanine nucleotides are quantitatively different from those of other GTPases. The intrinsic guanine nucleotide dissociation rates of FtsY are about 105 times higher than in Ras, but similar to those seen in GTPases in the presence of an exchange factor. Therefore, the data presented here show that the NG domain of FtsY resembles a GTPase–nucleotide exchange factor complex not only in its structure but also kinetically. The I-box, an insertion present in all SRP-type GTPases, is likely to act as an intrinsic exchange factor. From this we conclude that the details of the GTPase cycle of FtsY and presumably other SRP-type GTPases are fundamentally different from those of other GTPases.

Efficient allelic exchange and transposon mutagenesis in Mycobacterium tuberculosis

A better understanding of Mycobacterium tuberculosis virulence mechanisms is highly dependent on the design of efficient mutagenesis systems. A system enabling the positive selection of insertional mutants having lost the delivery vector was developed. It uses ts-sacB vectors, which combine the counterselective properties of the sacB gene and a mycobacterial thermosensitive origin of replication and can therefore be efficiently counterselected on sucrose at 39°C. This methodology allowed the construction of M. tuberculosis transposition mutant libraries. Greater than 106 mutants were obtained, far exceeding the number theoretically required to obtain at least one insertion in every nonessential gene. This system is also efficient for gene exchange mutagenesis as demonstrated with the purC gene: 100% of the selected clones were allelic exchange mutants. Therefore, a single, simple methodology has enabled us to develop powerful mutagenesis systems, the lack of which was a major obstacle to the genetic characterization of M. tuberculosis.

RecA tests homology at both pairing and strand exchange

RecA is a 38-kDa protein from Escherichia coli that polymerizes on single-stranded DNA, forming a nucleoprotein filament that pairs with homologous duplex DNA and carries out strand exchange in vitro. To observe the effects of mismatches on the kinetics of the RecA-catalyzed recombination reaction, we used assays based upon fluorescence energy transfer that can differentiate between the pairing and strand displacement phases. Oligonucleotide sequences that produced 2–14% mismatches in the heteroduplex product of strand exchange were tested, as well as completely homologous and heterologous sequences. The equilibrium constant for pairing decreased as the number of mismatches increased, which appeared to result from both a decrease in the rate of formation and an increase in the rate of dissociation of the intermediates. In addition, the rate of strand displacement decreased with increasing numbers of mismatches, roughly in proportion to the number of mismatches. The equilibrium constant for pairing and the rate constant for strand displacement both decreased 6-fold as the heterology increased to 14%. These results suggest that discrimination of homology from heterology occurs during both pairing and strand exchange.

Guanine nucleotide exchange factor GEF115 specifically mediates activation of Rho and serum response factor by the G protein α subunit Gα13

Signal transduction pathways that mediate activation of serum response factor (SRF) by heterotrimeric G protein α subunits were characterized in transfection systems. Gαq, Gα12, and Gα13, but not Gαi, activate SRF through RhoA. When Gαq, α12, or α13 were coexpressed with a Rho-specific guanine nucleotide exchange factor GEF115, Gα13, but not Gαq or Gα12, showed synergistic activation of SRF with GEF115. The synergy between Gα13 and GEF115 depends on the N-terminal part of GEF115, and there was no synergistic effect between Gα13 and another Rho-specific exchange factor Lbc. In addition, the Dbl-homology (DH)-domain-deletion mutant of GEF115 inhibited Gα13- and Gα12-induced, but not GEF115 itself- or Gαq-induced, SRF activation. The DH-domain-deletion mutant also suppressed thrombin- and lysophosphatidic acid-induced SRF activation in NIH 3T3 cells, probably by inhibition of Gα12/13. The N-terminal part of GEF115 contains a sequence motif that is homologous to the regulator of G protein signaling (RGS) domain of RGS12. RGS12 can inhibit both Gα12 and Gα13. Thus, the inhibition of Gα12/13 by the DH-deletion mutant may be due to the RGS activity of the mutant. The synergism between Gα13 and GEF115 indicates that GEF115 mediates Gα13-induced activation of Rho and SRF.

A Rap guanine nucleotide exchange factor enriched highly in the basal ganglia

Ras proteins, key regulators of growth, differentiation, and malignant transformation, recently have been implicated in synaptic function and region-specific learning and memory functions in the brain. Rap proteins, members of the Ras small G protein superfamily, can inhibit Ras signaling through the Ras/Raf-1/mitogen-activated protein (MAP) kinase pathway or, through B-Raf, can activate MAP kinase. Rap and Ras proteins both can be activated through guanine nucleotide exchange factors (GEFs). Many Ras GEFs, but to date only one Rap GEF, have been identified. We now report the cloning of a brain-enriched gene, CalDAG-GEFI, which has substrate specificity for Rap1A, dual binding domains for calcium (Ca2+) and diacylglycerol (DAG), and enriched expression in brain basal ganglia pathways and their axon-terminal regions. Expression of CalDAG-GEFI activates Rap1A and inhibits Ras-dependent activation of the Erk/MAP kinase cascade in 293T cells. Ca2+ ionophore and phorbol ester strongly and additively enhance this Rap1A activation. By contrast, CalDAG-GEFII, a second CalDAG-GEF family member that we cloned and found identical to RasGRP [Ebinu, J. O., Bottorff, D. A., Chan, E. Y. W., Stang, S. L., Dunn, R. J. & Stone, J. C. (1998) Science 280, 1082–1088], exhibits a different brain expression pattern and fails to activate Rap1A, but activates H-Ras, R-Ras, and the Erk/MAP kinase cascade under Ca2+ and DAG modulation. We propose that CalDAG-GEF proteins have a critical neuronal function in determining the relative activation of Ras and Rap1 signaling induced by Ca2+ and DAG mobilization. The expression of CalDAG-GEFI and CalDAG-GEFII in hematopoietic organs suggests that such control may have broad significance in Ras/Rap regulation of normal and malignant states.

Efficient loading of HLA-DR with a T helper epitope by genetic exchange of CLIP

The HLA class II-associated invariant chain (Ii)-derived peptide (CLIP) occupies the peptide binding groove during assembly in the endoplasmic reticulum, travels with HLA class II to endosomal compartments, and is subsequently released to allow binding of antigenic peptides. We investigated whether the exchange of CLIP with a known T helper epitope at the DNA level would lead to efficient loading of this helper epitope onto HLA class II. For this purpose, a versatile Ii-encoding expression vector was created in which CLIP can be replaced with a helper epitope of choice. Upon supertransfection of HLA-DR1-transfected 293 cells with an Ii vector encoding a known T helper epitope (HA307–319), predominantly length variants of this epitope were detected in association with the HLA-DR1 molecules of these cells. Moreover, this transfectant was efficiently recognized by a peptide-specific T helper clone (HA1.7). The results suggest that this type of Ii vector can be used to create potent class II+ cellular vaccines in which defined T cell epitopes are continuously synthesized.

Isolation of a brefeldin A-inhibited guanine nucleotide-exchange protein for ADP ribosylation factor (ARF) 1 and ARF3 that contains a Sec7-like domain

Brefeldin A (BFA) inhibited the exchange of ADP ribosylation factor (ARF)-bound GDP for GTP by a Golgi-associated guanine nucleotide-exchange protein (GEP) [Helms, J. B. & Rothman, J. E. (1992) Nature (London) 360, 352–354; Donaldson, J. G., Finazzi, D. & Klausner, R. D. (1992) Nature (London) 360, 350–352]. Cytosolic ARF GEP was also inhibited by BFA, but after purification from bovine brain and rat spleen, it was no longer BFA-sensitive [Tsai, S.-C., Adamik, R., Moss, J. & Vaughan, M. (1996) Proc. Natl. Acad. Sci. USA 93, 305–309]. We describe here purification from bovine brain cytosol of a BFA-inhibited GEP. After chromatography on DEAE–Sephacel, hydroxylapatite, and Mono Q and precipitation at pH 5.8, GEP was eluted from Superose 6 as a large molecular weight complex at the position of thyroglobulin (≈670 kDa). After SDS/PAGE of samples from column fractions, silver-stained protein bands of ≈190 and 200 kDa correlated with activity. BFA-inhibited GEP activity of the 200-kDa protein was demonstrated following electroelution from the gel and renaturation by dialysis. Four tryptic peptides from the 200-kDa protein had amino acid sequences that were 47% identical to sequences in Sec7 from Saccharomyces cerevisiae (total of 51 amino acids), consistent with the view that the BFA-sensitive 200-kDa protein may be a mammalian counterpart of Sec7 that plays a similar role in cellular vesicular transport and Sec7 may be a GEP for one or more yeast ARFs.

Cloning and expression of a cDNA encoding a bovine brain brefeldin A-sensitive guanine nucleotide-exchange protein for ADP-ribosylation factor

A 200-kDa guanine nucleotide-exchange protein (p200 or GEP) for ADP-ribosylation factors 1 and 3 (ARF1 and ARF3) that was inhibited by brefeldin A (BFA) was purified earlier from cytosol of bovine brain cortex. Amino acid sequences of four tryptic peptides were 47% identical to that of Sec7 from Saccharomyces cerevisiae, which is involved in vesicular trafficking in the Golgi. By using a PCR-based procedure with two degenerate primers representing sequences of these peptides, a product similar in size to Sec7 that contained the peptide sequences was generated. Two oligonucleotides based on this product were used to screen a bovine brain library, which yielded one clone that was a partial cDNA for p200. The remainder of the cDNA was obtained by 5′ and 3′ rapid amplification of cDNA ends (RACE). The ORF of the cDNA encodes a protein of 1,849 amino acids (≈208 kDa) that is 33% identical to yeast Sec7 and 50% identical in the Sec7 domain region. On Northern blot analysis of bovine tissues, a ≈7.4-kb mRNA was identified that hybridized with a p200 probe; it was abundant in kidney, somewhat less abundant in lung, spleen, and brain, and still less abundant in heart. A six-His-tagged fusion protein synthesized in baculovirus-infected Sf9 cells demonstrated BFA-inhibited GEP activity, confirming that BFA sensitivity is an intrinsic property of this ARF GEP and not conferred by another protein component of the complex from which p200 was originally purified.