Teratocarcinoma transplantation antigens are encoded in the H-2 region

Evidence is presented for the existence of teratocarcinoma transplantation antigens (Gt) encoded within the H-2 complex and present also on adult tissues. It has not been possible to separate these Gt loci from H-2 by recombination, and Gt factors map to each end of the H-2 complex. Previous reports indicating separation of all Gt loci from H-2 are reinterpreted. One class of such apparent recombinants has been shown to result from the outgrowth of tumor variants in mice of resistant genotype.Aspects of this work were presented at the 10th Cold Spring Harbor Conference on Cell Proliferation, September 1982.     

Characterization of presenilin-amyloid precursor interaction using bacterial expression and two-hybrid systems for human membrane proteins

An Escherichia coli system was used to produce the human membrane proteins presenilin 1 and amyloid precursor protein and to analyse their interaction. Our data indicate that the main binding site for amyloid precursor protein is located in the N-terminal three-transmembrane segments of presenilin and not in the proposed active site containing the two conserved aspartate residues. The data also suggest the presence of an additional segment of sufficient hydrophobicity at the C-terminus of PS1 to act potentially as a transmembrane segment. The implications of these findings for the function of γ-secretase are discussed.     

Kinetic effect of some aliphatic amines on yeast alcohol dehydrogenase.

Initial rate studies of ethanol oxidation catalyzed by yeast alcohol dehydrogenase (EC 1.1.1.1) were carried out in the presence of varying concentrations of aliphatic amines over the pH range from 8.0 to 10.5. Aliphatic amines either activate or inhibit the enzyme depending on whether the pH is greater or less than 9.5 suggesting that the protonated amines activate and the nonprotonated amines inhibit the enzyme. Aliphatic amines activate yeast alcohol dehydrogenase by decreasing Kb while they inhibit the enzyme by increasing both Ka and Kia. When both protonated and nonprotonated amines are present in solution, either overall activation or inhibition will be observed depending on the relative concentration of the two amine species.