Genetic, biochemical, and molecular characterization of nine glyceraldehyde-3-phosphate dehydrogenase mutants with reduced enzyme activity in Mus musculus.

The first mutations causing hereditary glyceraldehyde-3-phosphate dehydrogenase (GAPDH) deficiency in the mouse are described. In the course of various mutagenicity experiments with chemical mutagens and irradiation, nine independent mutations causing approximately 50-55% residual activity in blood compared to wild type were identified at the Gapdh structural locus on chromosome 6. Breeding experiments displayed an autosomal semidominant mode of inheritance for all mutants. Two mutations are homozygous viable producing a GAPDH residual activity of less than 10%. Mortality of the remaining seven homozygous lethal lines occurs at an early postimplantation stage of development. The physiologic and hematologic analyses provided no indication for further altered traits in heterozygotes or homozygotes. The molecular characterization showed base substitutions resulting in amino acid exchanges in seven mutations, in one mutation a transversion creating a stop codon caused a truncated protein of 89 amino acids and two deletions generating truncated proteins of 73 and 9 amino acids, respectively.