Requiring Fifty Three 1 Homolog (RFT1)

N-glycosylation of proteins follows a highly conserved pathway that begins with the synthesis of a Man(5)GlcNAc(2)-dolichylpyrophosphate (PP-Dol) intermediate on the cytoplasmic side of the endoplasmic reticulum (ER) membrane followed by the translocation of Man(5)GlcNAc (2)-PP-Dol to the luminal side of the ER membrane. RFT1 is the flippase enzyme that catalyzes this translocation.

Overexpression of Rft1 in delta-alg11 yeast suggested that Rft1 is the limiting component for the flipping of Man(5)GlcNAc(2)-PP-Dol from the cytoplasmic to luminal side of the ER membrane in vivo and that no additional factors are required. Rft1 depletion in yeast led to underglycosylation of the vacuolar N-linked glycoprotein carboxypeptidase Y.