alpha-1,6-mannosyltransferase activity GDP-Man:Man(2)GlcNAc(2)-PP-Dol alpha-1,6-mannosyltransferase activity https://github.com/geneontology/go-ontology/issues/22675 https://github.com/geneontology/go-ontology/issues/24984 https://github.com/geneontology/go-ontology/issues/30193 https://github.com/geneontology/go-ontology/issues/30326 MetaCyc:RXN-5463 GO:0102704 EC:2.4.1.257 molecular_function RHEA:29519 Catalysis of the reaction: an alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphospho-di-trans,poly-cis-dolichol + GDP-alpha-D-mannose = an alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphospho-di-trans,poly-cis-dolichol + GDP + H+. GlcNAc(2)-PP-Dol mannosyltransferase activity