SUMMARY PARAGRAPH for RER2
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 3). In mammals, dolichols with 19-22 isoprene units are the carrier molecules on which these steps occur.
RER2 encodes a cis-prenyltransferase that catalyzes the formation of dehydrodolichyl diphosphate, the committed step in dolichol synthesis, from farnesyl diphosphate and an isopentenyl pyrophosphate with 10-14 isoprene units. This results in the formation of a dolichol precursor with 14-18 isoprene units (2, 4). Rer2p is peripherally associated with the ER membrane (2, 4). RER2 is expressed in the early logarithmic phase (4). Overexpression of Erg20p, which synthesizes the Rer2p substrate farnesyl diphosphate, induces expression of RER2, SRT1, and DPM1.
Originally isolated as a mutant defective in retaining certain proteins in the ER (2), rer2 cells also grow slowly (2, 1) have defects in N-linked and O-linked glycosylation (2, 5), and form clumps when grown in suspension (2). They accumulate excessive ER and Golgi membrane material and are sensitive to hygromycin B and resistant to sodium orthovanadate (2).
Overexpression of the Rer2p homolog Srt1p, which synthesizes dolichol precursors with 19-22 isoprene units, suppresses deletion of RER2, but the resultant cells make only the longer-chain dolichols (2, 5). The rer2 srt1 double deletion is lethal (2).
The RER2 human homolog (OMIM), called hCIT(6) or hds (7) complements its deletion in yeast.
Last updated: 2005-07-08