GENETIC INFLUENCES ON ENZYME LOCALIZATION

Abstract

In mouse liver cells B-glucuronidase is present in approximately equal amounts in lysosomes and micro-somes, with an additional small amount in the soluble phase. Physical measurements indicate that it is the same enzyme at all sites. It had been previously shown that glucuronidase-deficient mouse strains exist and that the deficiency is controlled by a single gene (J. Nat. Cancer Inst. 10, 1949; 12, 1952). In animals of deficient strains the residual enzyme is present at the same intracellular sites but in altered proportions. Other enzymes present in lysosomes and micro-somes do not show similar differences. The gene for glucuronidase is closely linked to one controlling visual cell differentiation. Young mice, homozygous recessive at both loci, have a moderate enzyme level and normal visual cells. In such animals the onset of visual cell death occurs at approximately the same time during growth that the enzyme deficiency appears.