Distribution and characterization of hexose 6-phosphate dehydrogenase in trout

Electrophoretic analysis of trout liver extracts indicates that an autosomal gene coding for hexose 6-phosphate dehydrogenase (H6P D) in lake trout, Hpd-L, is monomorphic. In brook trout, the gene is polymorphic, having at least three genetic variants termed Hpd-B ¹, Hpd-B², and Hpd-B³. F ₁ hybrid splake exhibit the three expected phenotypes resulting from Hpd-L/Hpd-B ¹, Hpd-L/Hpd-B², and Hpd-L/Hpd-B ³ genotypes. Trout H6P D is ostensibly a dimer of mol wt 230,000. The characteristics of trout H6P D, including substrate specificity, genetic polymorphism, electrophoretic characteristics, subcellular localization, and tissue distribution are in close agreement with results obtained for mammalian H6P D. We suggest that trout and mammalian H6PDs, X-linked mammalian G6P D, and autosomal avian G6P D arose from a common ancestral type G6P D.The research was supported in part by National Science Foundation grant GB-7271 and by United States Public Health Service Predoctoral Fellowship 4 FO1 GM41704-03.