1.3.1.94 physiological function enzyme is necessary for the reduction of the alpha-isoprene unit of polyprenols to form dolichols, required for synthesis of dolichol-linked monosaccharides and the oligosaccharide precursor used for N-glycosylation 719256 1.3.1.94 physiological function Srd5a3 mutation is lethal in mouse and results in an activation of the unfolded protein response pathway 719256 1.3.1.94 physiological function the activities of yeast cis-prenyltransferases Rer2p and Srt1p and polyprenol reductase are not co-regulated and the reductase may be the rate-limiting enzyme in dolichol synthesis if the amount of polyisoprenoids synthesized exceeds a certain level 719005