Polymorphisms of human cholesterol 7 alpha-hydroxylase.
Human liver cholesterol 7 alpha-hydroxylase (CYP7) cDNAs were isolated from a human liver cDNA library. A full-length cDNA has 2901 nucleotides which encode a typical P450 polypeptide of 504 amino acid residues. Two different sequences of codon 100, TTT (Phe) and TCT (Ser), were identified in cDNA clones. In addition, codons 347 and 385 are GAT (Asp) and GAC (Asp) in all cDNA clones, whereas those reported previously (FEBS Lett. 268, 137-140, 1990) are AAT (Asn) and AGC (Ser), respectively. Since there is only one 7 alpha-hydroxylase gene in the human genome, it is likely that polymorphisms at the codon 100 of cDNA clones arise from two different alleles in the 7 alpha-hydroxylase gene of this human liver.