Molecular cloning and characterization of the cDNA encoding the rat liver gamma-butyrobetaine hydroxylase

Carnitine biosynthesis from lysine and methionine involves five enzymatic r eactions, gamma-butyrobetaine hydroxylase (BBH; EC 1.14.11.1) is the last e nzyme of this pathway. It catalyzes the reaction of hydroxylation of gamma- butyrobetaine to carnitine. The cDNA encoding this enzyme has been isolated and characterized. The cDNA contained an open reading frame of 1161 bp enc oding a protein of 387 amino acids with a deduced molecular weight of 44.5 kDa. The sequence of the cDNA showed an important homology with the human c DNA recently isolated. Northern analysis showed gamma-butyrobetaine hydroxy lase expression in the liver and in some extend in the testis and the epidi dymis. During this study, it also appeared that BBH mRNA expression was und etectable by Northern analysis during the perinatal period. During the deve lopment of the rat, the amount of BBH mRNA appeared after the weaning of th e young rat and reached a maximal expression at the adult stage. (C) 1999 E lsevier Science B.V. All rights reserved.