1,3-beta-D-glucan synthase activity https://github.com/geneontology/go-ontology/issues/30193 (1,3)-beta-glucan (callose) synthase activity UDPglucose:1,3-beta-D-glucan 3-beta-D-glucosyltransferase activity UDP-glucose:(1,3)beta-glucan synthase activity beta-1,3-glucan synthase activity beta-1,3-glucan synthetase activity GO:0003843 GO:0009981 GS-II UDP-glucose-1,3-beta-D-glucan glucosyltransferase activity 1,3-beta-glucan synthase activity 1,3-beta-glucan-uridine diphosphoglucosyltransferase activity UDP-glucose-1,3-beta-glucan glucosyltransferase activity uridine diphosphoglucose-1,3-beta-glucan glucosyltransferase activity RHEA:21476 Catalysis of the reaction: UDP-glucose + [(1->3)-beta-D-glucosyl](n) = UDP + [(1->3)-beta-D-glucosyl](n+1). EC:2.4.1.34 callose synthase activity UDP-glucose-beta-glucan glucosyltransferase activity callose synthetase activity 1,3-beta-D-glucan-UDP glucosyltransferase activity paramylon synthetase UDPglucose-1,3-beta-D-glucan glucosyltransferase activity 1,3-beta-D-glucan synthetase activity UDP-glucose:1,3-beta-D-glucan 3-beta-D-glucosyltransferase activity MetaCyc:13-BETA-GLUCAN-SYNTHASE-RXN molecular_function UDP-glucosyltransferase activity