GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase (EC 2.4.1.252 GumH AceA alpha13-mannosyltransferase AceA) is an enzyme with system name GDP-mannose:D-Glc-beta-(1->4)-Glc-alpha-1-diphospho-ditransoctacis-undecaprenol 3-alpha-mannosyltransferase .