SUMMARY PARAGRAPH for SEC59
Dolichols are a class of polyisoprenoid alcohols with five or more isoprene units in which the C2-C3 bond is saturated. In yeast, dolichols with 14-18 isoprene units are the carrier molecules on which many of the steps in N-linked glycosylation, O-linked glycosylation, and GPI anchor synthesis occur on the membrane of the endoplasmic reticulum (ER) (reviewed in 4). In mammals, dolichols with 19-22 isoprene units are the carrier molecules on which these steps occur.
SEC59 encodes dolichol kinase (3), which synthesizes dolichyl-phosphate (Dol-P), the substrate on which oligosaccharide cores are assembled on the ER membrane. Mutants lacking Sec59p produce poorly N-glycosylated proteins that accumulate in the ER, hence the secretory phenotype (5). Dol-P is also used to shuttle mannose (and glucose) into the ER, so sec59 mutants are also deficient in O-linked glycosylation and GPI anchor synthesis (6, 7). (Refer to the entries for DPM1 and ALG5 for information on shuttling mannose and glucose, respectively, into the ER.) A putative human dolichol kinase cDNA complements the sec59-1 mutation (8).
Last updated: 2005-07-01