Molecular cloning of testicular 20 alpha-hydroxysteroid dehydrogenase: identity with aldose reductase.
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Complementary DNA (cDNA) clones encoding bovine testicular 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) have been isolated from a bovine testicular lambda gt11 library using polyclonal antibodies against 20 alpha-HSD and DNA probe hybridization. Nucleotide sequencing of three independently isolated clones was used to establish a composite cDNA sequence that encodes the enzyme. It contains a coding sequence of 921 nucleotides, a stop codon, and a 264-nucleotide 3'-noncoding segment which allowed deduction of the amino acid sequence of the enzyme. A computer homology search of the 20 alpha-HSD cDNA performed against the GenBank DNA sequence database revealed it to be identical with bovine lens aldose reductase (alditol:NADPH oxidoreductase; EC 184.108.40.206), and a literature search reveals the deduced amino acid sequence to be identical with that reported for the bovine enzyme. Sequences obtained from the N-terminus of purified testicular 20 alpha-HSD and from random peptides obtained by treatment with endopeptidase Lys-C are all identical with regions of the deduced amino acid sequence of 20 alpha-HSD and/or the published sequence of aldose reductase. Further, the enzyme purified to homogeneity by following activity with 17-hydroxyprogesterone as a substrate was shown to reduce glucose, glyceraldehyde, and benzaldehyde (all classic aldose reductase substrates). Finally, 17-hydroxyprogesterone inhibited the reduction of benzaldehyde and glyceraldehyde. Because aldose reductase has been implicated in the etiology of diabetic complications, acceptance of steroid substrates may offer new implications for therapy.
author list (cited authors)
Warren, J. C., Murdock, G. L., Ma, Y., Goodman, S. R., & Zimmer, W. E.
complete list of authors
Warren, JC||Murdock, GL||Ma, Y||Goodman, SR||Zimmer, WE