The cDNA sequence of the lactate dehydrogenase-A (LDH-A) of the spiny dogfish was determined. The deduced amino acid sequence differed from a previously determined protein sequence by 5%. Separate maximum parsimony analyses of the two sequences along with LDHs of other vertebrates resulted in shorter trees with the sequence presented here, as well as fewer equally parsimonious trees. The new sequence also indicates a greater conservation of length among vertebrate LDHs than was previously suspected. Analyses of the phylogeny of vertebrate LDHs resulted in a monophyletic grouping of LDH-As, from within which mammalian LDH-C is derived. The phylogeny of LDH-As did not exactly match the phylogeny of the organisms, raising the possibility of multiple origins and losses of a muscle-predominant gene. LDH-Bs appear to have shared a single origin.
Amino Acid Sequence Animals