ESTIMATION OF THE RATE OF GLYCEROL 3-PHOSPHATE DEHYDROGENASE EVOLUTION IN HIGHER VERTEBRATES.

Abstract

Among proteins which have been examined for polymorphism in natural populations, sn-glycerol 3-phosphate dehydrogenase (E.C. 1.1.1.8) is one of the least polymorphic (Ayala et al., 1974; Collier and Maclntyre, 1977, 1978; Lakovaara et al., 1977; Coyne et al., 1979; Johnson, 1979). These studies have also indicated that the enzyme, also known as aXGPDH, is evolving rather slowly. It is possible that limited polymorphism is correlated with slow rates of amino acid replacement (Skibinski and Ward, 1982); however, for most enzymes whose natural polymorphism has been well-studied there are very few amino acid sequence data. Such is the case for glycerol 3-phosphate dehydrogenase. The only published sequence is for the rabbit muscle enzyme (Otto et al., 1977, 1980). The structure of the Drosophila enzyme is under study (Niesel et al., 1982). Glycerol 3-phosphate dehydrogenase is a cytosolic enzyme present in most tissues of all eukaryotes. In vertebrates amounts of this enzyme are particularly high in liver and white skeletal muscle, but relatively low in heart, brain, and most neoplastic tissues (Young and Pace, 1958). This enzyme is particularly concentrated in the flight muscles of insects such as bees and flies (Crabtree and Newsholme, 1972) where the enzyme