Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis: V. Genetic polymorphism of cytosol 31k polypeptide.

Three different electrophoretic types (1-1, 2-1 and 2-2) of a human cellular polypeptide with molecular weight of 31 000 have been identified by the analysis of PHA-stimulated peripheral blood lymphocyte proteins using high resolution two-dimensional gel electrophoresis. Family and population studies indicate that the three phenotypes of the polypeptide are determined by two common alleles at a single autosomal locus. The 31k polypeptide appears to be present as a monomer in the cytosol in a wide range of different cell types, including permanent lymphoblastoid cell lines, fibroblasts and HeLa cells. In an individual with the 31k polypeptide type 2-2, the phenotypes of adenosine deaminase and uridine monophosphate kinase were both type 1. These data indicate that the 31K polypeptide is a new polymorphic protein encoded by a new autosomal locus. It is proposed that the polypeptide and its locus be temporarily designated cytosol 31k polypeptide (C31k polypeptide) and C31P, respectively. In a Japanese population, the gene frequencies of C31P1 and C31P2 were 0.940 and 0.060, respectively. The C31k polypeptide type 2-2 appears to be a molecular weight variant as well as a charge variant.