dol-P-Man:Man(2)GlcN-acyl-PI alpha-1,2-mannosyltransferase activity
dol-p-man:man(2)glcn-acyl-pi alpha-1,2-mannosyltransferase activity
Catalysis of the transfer of an alpha-D-mannosyl residue from dolichol-P-mannose to Man(2)-GlcN-acyl-PI, forming an alpha-(1->2)-D-mannosyl-D-mannose linkage. This transfers the third mannose to the GPI precursor.