24,25-Dihydroxycholecalciferol

24,25-Dihydroxycholecalciferol, also known as 24,25-dihydroxyvitamin D3 and (24R)-hydroxycalcidiol (abbreviated as 24(R),25-(OH)2D3), is a compound which is closely related to 1,25-dihydroxyvitamin D3, the active form of vitamin D3, but like vitamin D3 itself and 25-hydroxyvitamin D3 is inactive as a hormone both in vitro and in vivo. It was identified by Michael F. Holick.24,25-dihydroxyvitamin D3 is formed from 25-hydroxyvitamin D3 by the action of P450cc24 (25-hydroxyvitamin D3-24-hydroxylase), which appears to be 'a multicatalytic enzyme catalyzing most, if not all, of the reactions in the C-24/C-23 pathway of 25-OH-D3 metabolism.' It has been proposed that 24,25-dihydroxyvitamin D3 is a metabolite of 25-hydroxyvitamin D3 which is destined for excretion.Click on genes, proteins and metabolites below to link to respective articles.