An allele (Pk-1b) from wild-caught mice that affects the activity and kinetics of erythrocyte and liver pyruvate kinase.

A true breeding strain was made from a wild-caught mouse with low erythrocyte pyruvate kinase (E.C. 2.7.1.40) activity. This variation showed additive inheritance and segregated as an allele at a single locus (Pk-1b). Mice homozygous for the reduced blood pyruvate kinase activity cosegregated for reduced liver activity. In both these tissues the variant enzyme had a lowered heat stability and reduced Km values for ADP. An increased stimulation by FDP was also detected in the liver pyruvate kinase. No difference in the isoelectric point of the variant enzyme in either erythrocyte or liver was observed when compared with the enzyme from C57BL mice (Pk-1a/Pk-1a). It is concluded that Pk-1 is the structural gene for the erythrocyte and the major liver pyruvate kinase. No other tissue pyruvate kinase showed altered characteristics.