Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis. VIII. Genetic polymorphism of cytosol polypeptide with molecular weight of 20,000.

We describe a genetic polymorphism of cytosol polypeptide with mol. wt. of 20,000 detected in lymphocytes and erythrocytes by two-dimensional gel electrophoresis. Three different electrophoretic phenotypes (type 1-1, 2-1, and 2-2) of the polypeptide have been identified in a Japanese population. Family studies indicate that the phenotypes are determined by two common alleles at a single autosomal locus. The polypeptide is present in the cytosol of various kinds of cells and is abundant in erythrocytes. The data on a gel filtration of the erythrocyte cytosol proteins on a Sephadex G-100 column suggest that the polypeptide exists as a dimer in cells. In nine out of 79 individuals, the phenotypes of the polypeptide were different from those of glyoxalase 1 (GLO1) which has similar properties in subunit size, cell distribution, and allele frequencies. These data indicate that the polypeptide with mol. wt. of 20,000 is a new polymorphic cellular polypeptide. We propose that the polypeptide be temporarily designated as cytosol polypeptide with mol. wt. of 20,000 (CP20) and that the gene for CP20 be designated as CP20. The gene frequencies of two common alleles (CP20(1) and CP20(2) are 0.955 and 0.045, respectively, in a Japanese population.