title: Rat testis P-450(17)alpha cDNA: the deduced amino acid sequence, expression and secondary structural configuration.
abstract: A complete amino acid sequence for rat testis P-450(17)alpha was deduced from nucleotide analysis of a cDNA clone isolated from a rat Leydig cell cDNA library. This DNA clone, containing initiation and termination codons and a polyA tail, translated a polypeptide in COS-1 cells that expressed both 17 alpha-hydroxylase and 17,20 lyase activities. It exhibited significant similarity to the nucleotide and deduced amino acid sequences of the bovine and human cytochrome P-450(17)alpha, particularly with respect to the highly conserved regions and secondary structure. The P-450(17)alpha appears to be anchored to the membrane of the endoplasmic reticulum through two transmembrane regions, specifically the N terminal insertion peptide and the stop-transfer sequence. Hydropathic analysis indicates that the remainder of the C terminus is associated with the membrane through four hydrophobic clefts, including the putative steroid binding site.
authors.affiliation: Section on Molecular Endocrinology, Endocrinology National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
authors.forename: M
authors.initials: M
authors.lastname: Namiki
authors.forename: M
authors.initials: M
authors.lastname: Kitamura
authors.forename: E
authors.initials: E
authors.lastname: Buczko
authors.forename: M L
authors.initials: ML
authors.lastname: Dufau
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003198:Computer Simulation; D004247:DNA / Q000235:genetics; D005786:Gene Expression Regulation; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011374:Progesterone / Q000378:metabolism; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics*; D013737:Testis / Q000502:physiology*; D014162:Transfection
chemical_list: D008565:Membrane Proteins; D012333:RNA, Messenger; D011374:Progesterone; D004247:DNA; D013250:Steroid Hydroxylases; D013254:Steroid 17-alpha-Hydroxylase