Putative alpha-1,2-glucosyltransferase, which adds the third glucose residue to the lipid-linked oligosaccharide precursor for N-linked glycosylation. Transfers glucose from dolichyl phosphate glucose (Dol-P-Glc) onto the lipid-linked oligosaccharide Glc(2)Man(9)GlcNAc(2)-PP-Dol (By similarity). When coupled to KCNH2 may reduce KCNH2 sensitivity to classic proarrhythmic drug blockade, possibly by mediating glycosylation of KCNH2 (PubMed:14525949). Has a role in maintenance of cochlear outer hair cell function (By similarity). a dolichyl beta-D-glucosyl phosphate + alpha-D-Glc-(1->3)-alpha-D-Glc-(1->3)-alpha-D-Man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->6)]-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol = a dolichyl phosphate + alpha-D-Glc-(1->2)-alpha-D-Glc-(1->3)-alpha-D-Glc-(1->3)-alpha-D-Man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->6)]-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol + H(+) Protein modification; protein glycosylation. Interacts with KCNH1 and KCNH2. Highly expressed in heart, placenta, liver, kidney and pancreas. Weakly expressed in lung, skeletal muscle and brain. Genetic variations in ALG10B may reduce susceptibility to acquired long QT syndrome. Belongs to the ALG10 glucosyltransferase family. PubMed:15280551 reports a Val-447 variant, however there is evidence that the right variant is Val-446.