Cholesterol is hydroxylated to 7alpha-hydroxycholesterol by CYP7A1 Authored: Jassal, B, 2008-05-19 12:57:01 Cholesterol + NADPH + H+ + O2 => 7-alpha-hydroxycholesterol + NADP+ + H2O Cholesterol, NADPH + H+, and O2 form 7alpha-cholesterol (5-cholesten-3beta, 7alpha-diol), NADP+,and H2O, in a reaction catalyzed by CYP7A1 (cholesterol 7alpha-hydroylase) in the endoplasmic reticulum membrane. In the body, this enzyme is expressed only in liver, and its expression is tightly regulated at the level of transcription to determine the overall rate of bile acid and bile salt production (Russell 2003; Pullinger et al. 2002). EC Number: 1.14.13.17 Edited: D'Eustachio, P, 2007-02-17 19:40:28 Pubmed12093894 Pubmed12543708 Pubmed2384150 Reactome Database ID Release 43192051 Reactome, http://www.reactome.org ReactomeREACT_10052 Reviewed: D'Eustachio, P, 2008-05-28 08:30:54