Dolichol kinase activity: a key factor in the control of N-glycosylation in inner mitochondrial membranes

Abstract

Inner mitochondrial membranes from liver contain a dolichol kinase which required CTP as a phosphoryl donor. Kinase activity was linear with protein concentration and unlike other reported kinases, activated almost equally well by Mg 2+, Mn 2+ or Ca 2+. Thin-layer chromatography showed that the reaction product co-migrated with authentic dolichyl monophosphate. The phosphorylation of dolichol did not occur in presence of ATP, GTP or UTP but required exogenous dolichol for maximal activity. Newly synthesized [ 3H]dolichyl monophosphate has been shown to be glycosylated in the presence of GDP[ 14C]mannose or UDP[ 14C]glucose. The double labeled lipids formed by the sugar nucleotide-dependent reactions were identified respectively as [ 14C]mannosylphosphoryl[ 3H]dolichol and [ 14C]glucosylphosphoryl[ 3H]dolichol. These results are discussed in terms of regulation of N-glycosylation processes in inner mitochondrial membranes from liver.