Dolichyl Phosphate Mannosyltransferase Polypeptide 1 (DPM1)

Dolichol-phosphate mannose (Dol-P-Man) serves as a donor of mannosyl residues on the lumenal side of the endoplasmic reticulum (ER). Lack of Dol-P-Man results in defective surface expression of GPI-anchored proteins. Dol-P-Man is synthesized from GDP-mannose and dolichol-phosphate on the cytosolic side of the ER by the enzyme dolichyl-phosphate mannosyltransferase. Human DPM1 lacks a carboxy-terminal transmembrane domain and signal sequence and is regulated by DPM2.

The predicted 260-amino acid human protein shares approximately 30% identity with yeast dpm1. However, DPM1 lacks the C-terminal transmembrane domain found in dpm1 and does not contain a signal sequence.