MOLECULAR-CLONING AND FUNCTIONAL EXPRESSION OF THE CYTOCHROME-P450 11B-HYDROXYLASE OF THE GUINEA-PIG

A cDNA library has been constructed from adrenal glands of guinea pigs receiving a low sodium/high potassium diet. From this library a compl ementary DNA encoding an 11 beta-hydroxylase (EC 1.14.15.4) was isolat ed. Northern blot analysis revealed a major transcript of 2.2 kb size. The cDNA was cloned into an eucaryotic expression vector and the acti vity of the enzyme towards various substrates was investigated after e xpression in COS-1 cells. The enzyme was able to perform 11 beta-hydro xylations of 11-deoxycorticosterone, 11-deoxycortisol and androstendio ne as well as 18-hydroxylations and 19-hydroxylations to a small exten t. Phylogenetic analyses with thirteen protein sequences of the CYP11B subfamily showed an early divergence of the guinea pig, but could not establish a definite branching order. (C) 1996 Academic Press, Inc.