Mutation of Pro-258 in transmembrane domain 6 constitutively activates the G protein-coupled alpha-factor receptor.

The alpha-factor pheromone receptor stimulates MATa yeast cells to undergo conjugation. The receptor contains seven transmembrane domains that function in ligand binding and in transducing a signal to the cytoplasmic receptor sequences to mediate G protein activation. A genetic screen was used to isolate receptor mutations that constitutively signal in the absence of alpha-factor. The Pro-258-->Leu (P258L) mutation caused constitutive receptor signaling that was equivalent to about 45% of the maximum level observed in wild-type cells stimulated with alpha-factor. Mutations of both Pro-258 and the adjacent Ser-259 to Leu increased constitutive signaling to > or = 90% of the maximum level. Since Pro-258 occurs in the central portion of transmembrane domain 6, and since proline residues are expected to cause a kink in alpha-helical domains, the P258L mutation is predicted to alter the structure of transmembrane domain 6. The P258L mutation did not result in a global distortion of receptor structure because alpha-factor bound to the mutant receptors with high affinity and induced even higher levels of signaling. These results suggest that sequences surrounding Pro-258 may be involved in ligand activation of the receptor. Conformational changes in transmembrane domain 6 may effect a change in the adjacent sequences in the third intracellular loop that are thought to function in G protein activation. Greater than 90% of all G protein-coupled receptors contain a proline residue at a similar position in transmembrane domain 6, suggesting that this aspect of receptor activation may be conserved in other receptors.

Mass of particulate carbon and nitrogen in suspended matter as a function of volume filtered in several oceanic areas

We address two issues in the determination of particulate carbon and nitrogen in suspended matter of aquatic environments. One is the adsorption of dissolved organic matter on filters, leading to overestimate particulate matter. The second is the material loss during filtration due to fragile algal cells breaking up. Examples from both laboratory cultures and natural samples are presented. We recommend using stacked filters in order to estimate thefirst and filtering different volumes of water in order to evaluate the second.

Memorandum on the law and the facts in the matter of the claim of China against Mexico for losses of life and property suffered by Chinese subjects at Torreón on May 13, 14, and 15, 1911.

"English & Spanish."

Referee's memorandum and award in the matter of: Whether further wage increases are justified ... in relation to employees represented by 15 cooperating railway labor organizations, Brotherhood of Railroad Trainmen, Brotherhood of Locomotive Engineers, Brotherhood of Locomotive Firemen and Enginemen, Order of Railway Conductors, and railroads as represented by Eastern, Western and Southeastern carriers; Conference committees, before Paul N. Guthrie.

Mode of access: Internet.

In the matter of: public hearing before Special Industry Committee no. 41-B for the food and related products industry in Puerto Rico. September 11, 15, and 16, 1958 ... San Juan, Puerto Rico. Reporters: John F. Hrozencik [a [and] Genevieve Biolsi.

Maynard E. Pirsig, chairman.

In the matter of: public hearing before Special Industry Committee no. 41-C for the paper, paper products, printing, and publishing industry in Puerto Rico. 17, 18, and 19 September, 1958 ... San Juan, Puerto Rico. Reporters: John F. Hrozencik [and] Genevieve Biolsi.

Maynard E. Pirsig, chairman.

In the matter of: public hearing before Special Industry Committee no. 41-A for the chemical, petroleum, rubber, and related products industry in Puerto Rico. September 3, 4, and 5, 1958 ... San Juan Puerto Rico. . Reporters: John F. Hrozencik [and] Genevieve Biolsi.

Maynard E. Pirsig, chairman.

In the matter of: public hearing before Special Industry Committee no. 41-D for the lumber and wood products industry in Puerto Rico. September 23, 1958 ... San Juan, Puerto Rico. Reporters: Genevieve Biolsi [and] John F. Hrozencik.

Maynard E. Pirsig, chairman.