Characterization of cDNAs encoding the rat testis-specific E1 alpha subunit of the pyruvate dehydrogenase complex: comparison of expression of the corresponding mRNA with that of the somatic E1 alpha subunit.

cDNA clones encoding the testis-specific form of the rat pyruvate dehydrogenase complex E1 alpha subunit have been isolated. Comparison of the predicted amino acid sequence with those of the somatic and testis-specific E1 alpha forms of man and mouse and the somatic E1 alpha form of rat indicates the change of a serine residue, believed to be phosphorylated in vivo by pyruvate dehydrogenase E1 alpha-specific kinase, to an alanine at position 233. The implications of this change are discussed. Northern blot analysis and RNase protection assays indicate that the expression of mRNA encoding testis-specific E1 alpha subunit is restricted to testis whereas mRNA for the somatic form is found in all tissues analyzed, albeit in very small amounts in testis.