Gene conversion and differential regulation in the rat P-450 IIA gene subfamily. Purification, catalytic activity, cDNA and deduced amino acid sequence, and regulation of an adult male-specific hepatic testosterone 15 alpha-hydroxylase.

摘要: Previous studies on regulation of the rat hepatic P-450 IIA1 cDNA have provided evidence for a second gene closely related to but regulated in manner quite distinct from IIA1. Experiments were carried out isolate this gene, designated IIA2, order study more directly its and relationship A full length IIA2 was isolated an adult male liver lambda gt11 library sequenced completely. The shared 93% nucleotide 88% deduced amino acid similarities with previously characterized (Nagata, K., Matsunaga, T., Gillette, J., Gelboin, H. V., Gonzalez, F. J. (1987) Biol. Chem. 262, 2787-2793). protein, cDNA, contained 492 acids calculated Mr 56,352. Comparison cDNAs revealed areas low similarity interspersed absolute identity, suggesting that conversions played role evolution IIA subfamily. Expression mRNAs during development studied use specific oligonucleotide probes. mRNA increased within 1 week after birth both female rats; however, postpubertal expression decreased males yet remained elevated females. In contrast, markedly induced at puberty not detectable females any age examined. Furthermore, only by treatment rats 3-methylcholanthrene. Although actively expressed tissue, no their found lung, kidney, or intestine, genes tissue-specific promoters. Reconstituted enzyme assays purified protein products showed that, although enzymes share considerable sequence similarity, positional specificities toward prototype substrate testosterone are strikingly different.