In enzymology, a dolichyl-phosphate-mannose-protein mannosyltransferase (EC 2.4.1.109) is an enzyme that catalyzes the chemical reaction

dolichyl phosphate D-mannose + protein ${\displaystyle \rightleftharpoons }$ dolichyl phosphate + O-D-mannosylprotein

Thus, the two substrates of this enzyme are dolichyl phosphate D-mannose and protein, whereas its two products are dolichyl phosphate and O-D-mannosylprotein.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is dolichyl-phosphate-D-mannose:protein O-D-mannosyltransferase. Other names in common use include dolichol phosphomannose-protein mannosyltransferase, and protein O-D-mannosyltransferase. A human gene that codes for this enzyme is POMT1.

• Babczinski P, Haselbeck A, Tanner W (1980). "Yeast mannosyl transferases requiring dolichyl phosphate and dolichyl phosphate mannose as substrate. Partial purification and characterization of the solubilized enzyme". Eur. J. Biochem. 105 (3): 509–15. doi:10.1111/j.1432-1033.1980.tb04526.x. PMID 6989607.
• Palamarczyk G, Lehle L, Mankowski T, Chojnacki T, Tanner W (1980). "Specificity of solubilized yeast glycosyl transferases for polyprenyl derivatives". Eur. J. Biochem. 105 (3): 517–23. doi:10.1111/j.1432-1033.1980.tb04527.x. PMID 6445267.