title: The porcine taurochenodeoxycholic acid 6alpha-hydroxylase (CYP4A21) gene: evolution by gene duplication and gene conversion.
abstract: Porcine taurochenodeoxycholic acid 6alpha-hydroxylase, cytochrome P450 4A21 (CYP4A21), differs from other members of the CYP4A subfamily in terms of structural features and catalytic activity. CYP4A21 participates in the formation of hyocholic acid, a species-specific primary bile acid in the pig. The CYP4A21 gene was investigated and found to be approx. 13 kb in size and split into 12 exons. The intron-exon organization of the CYP4A21 gene corresponds to that of CYP4A fatty acid hydroxylase genes in other species. Comparison with a genomic segment of a pig CYP4A fatty acid hydroxylase gene ( CYP4A24 ) revealed a sequence identity with CYP4A21 that extends beyond the exons, indicating a common origin by gene duplication. A pronounced sequence identity was found also within the proximal 5'-flanking regions, whereas the patterns of mRNA expression of CYP4A21 and CYP4A fatty acid hydroxylases in pig liver differ. Sequence comparison aiming to elucidate the origin of the unique features of CYP4A21 revealed a region of decreased sequence identity from exon 6 to exon 8, strongly suggesting that gene conversion could have contributed to the evolution of CYP4A21.
authors.affiliation: Division of Biochemistry, Department of Pharmaceutical Biosciences, University of Uppsala, Box 578, S-751 23 Uppsala, Sweden. Kerstin.Lundell@farmbio.uu.se
authors.forename: Kerstin
authors.initials: K
authors.lastname: Lundell
mesh_terms: D024506:5' Flanking Region; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics*; D019143:Evolution, Molecular; D005785:Gene Conversion; D020440:Gene Duplication; D040481:Genome Components; D006899:Mixed Function Oxygenases / Q000235:genetics; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment; D013250:Steroid Hydroxylases / Q000096:biosynthesis / Q000235:genetics*; D013552:Swine / Q000235:genetics*
chemical_list: D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D013250:Steroid Hydroxylases; C454259:cytochrome P-450 4A24 (porcine); C095246:taurochenodeoxycholic acid 6-alpha-hydroxylase