Mannose P Dolichol Utilization Defect Protein 1 (MPDU1)

MPD synthase (DPM1) catalyzes the synthesis of mannose-P-dolichol (MPD), an essential sugar donor for glycoconjugates and an essential substrate for synthesis of glycosylphosphatidylinositols (GPIs). The Chinese hamster ovary (CHO) Lec15 and Lec35 mutant cells are defective in synthesis and utilization, respectively, of MPD. The SL15 cDNA also suppressed the Lec35 mutation. Sequence analysis indicated that SL15 encodes a transmembrane protein with cytosolic C and N termini. There was no significant sequence similarity between SL15 and the S. cerevisiae MPD synthase, leading the authors to suggest that SL15 plays a distinct role in MPD synthesis. Mao et al. (1998) identified an umbilical cord blood CD34-positive cell cDNA encoding the human homolog of SL15. The predicted human protein contains 247 amino acids.