Identification of a cytochrome b-type NAD(P)H oxidoreductase ubiquitously expressed in human cells

Cytochrome b-type NAD(P)H oxidoreductases are involved in many physiological processes, including iron uptake in yeast, the respiratory burst, and perhaps oxygen sensing in mammals. We have identified a cytosolic cytochrome b-type NAD(P)H oxidoreductase in mammals, a flavohemoprotein (b5+b5R) containing cytochrome b5 (b5) and b5 reductase (b5R) domains. A genetic approach, using blast searches against dbest for FAD-, NAD(P)H-binding sequences followed by reverse transcription–PCR, was used to clone the complete cDNA sequence of human b5+b5R from the hepatoma cell line Hep 3B. Compared with the classical single-domain b5 and b5R proteins localized on endoplasmic reticulum membrane, b5+b5R also has binding motifs for heme, FAD, and NAD(P)H prosthetic groups but no membrane anchor. The human b5+b5R transcript was expressed at similar levels in all tissues and cell lines that were tested. The two functional domains b5* and b5R* are linked by an approximately 100-aa-long hinge bearing no sequence homology to any known proteins. When human b5+b5R was expressed as c-myc adduct in COS-7 cells, confocal microscopy revealed a cytosolic localization at the perinuclear space. The recombinant b5+b5R protein can be reduced by NAD(P)H, generating spectrum typical of reduced cytochrome b with alpha, beta, and Soret peaks at 557, 527, and 425 nm, respectively. Human b5+b5R flavohemoprotein is a NAD(P)H oxidoreductase, demonstrated by superoxide production in the presence of air and excess NAD(P)H and by cytochrome c reduction in vitro. The properties of this protein make it a plausible candidate oxygen sensor.

Geological-seismological evaluation of earthquake hazards at Franklin Falls Damsite, New Hampshire /

Abstract.

Thirty years in the Arctic regions : a narrative of the explorations and adventures of Sir John Franklin

"Copyright by the Keystone Publishing Co." -- T.p. verso

Catalogo do Gabinete Português de Leitura no Rio de Janeiro organizado segundo o systema decimal de Melvil Dewey, pelo Dr. Benjamin Franklin Ramiz Galvão.

Vol. 2 contains an alphabetical subject index.

A lecture on the life of Dr. Franklin /

"The profits of this work, both in England and America, will be applied in aid of the London Printers' Pension Society".

The true Benjamin Franklin,

Mode of access: Internet.

Bibliotheca Wiffeniana. Spanish reformers of two centuries from 1520; their lives and writings, according to the late Benjamin B. Wiffen's plan and with the use of his materials.

Reprint of the 1874-1904 ed.

Kitāb al-ʻAhd al-Jadīd li-rabbinā wa-mukhalliṣinā Yasūʻ al-Masīḥ [microform].

Edited by Franklin E. Hoskins.

Anatomical terminology, with special reference to the <B N A>

Mode of access: Internet.

Map of Holmes Island and the adjoining upland : the property of R. B. Mason Esq.

Scale not given.