title: The gamma 1 and gamma 2 subunits of human liver alcohol dehydrogenase. cDNA structures, two amino acid replacements, and compatibility with changes in the enzymatic properties.
abstract: cDNA clones corresponding to two alleles of the ADH3 locus were identified by hybridization with synthetic oligodeoxyribonucleotides specific for class I human liver alcohol dehydrogenase. Sequences were determined for a 1457-nucleotide cDNA, covering the whole gamma 2-coding region, and a 1224-nucleotide cDNA, including the region coding for amino acid residues 53-374 of the gamma 1 subunit. Two amino acid replacements between the gamma 1 and gamma 2 subunits were identified. At position 349, isoleucine in gamma 1 instead of valine in gamma 2 is a conservative exchange of a superficial residue which has been ascribed no special importance. The other exchange, at position 271, arginine in gamma 1 and glutamine in gamma 2, explains differences in enzyme properties. Electrophoretically, it is consistent with the less cathodic mobility of the gamma 2 subunit. Functionally, the location of the exchange at the surface of the coenzyme-binding pocket may influence the dissociation of the reduced coenzyme.
mesh_terms: D000426:Alcohol Dehydrogenase / Q000032:analysis* / Q000235:genetics; D000595:Amino Acid Sequence; D001483:Base Sequence; D003067:Coenzymes / Q000032:analysis; D004247:DNA / Q000032:analysis*; D006801:Humans; D008099:Liver / Q000201:enzymology*
chemical_list: D003067:Coenzymes; D004247:DNA; D000426:Alcohol Dehydrogenase