Catalyzes the glycosylation of anthocyanins from UDP-glucose. a 5-hydroxy anthocyanidin + UDP-alpha-D-glucose = an anthocyanin 5-O-beta-D-glucoside + H(+) + UDP Pigment biosynthesis; anthocyanin biosynthesis. By PAP1. Belongs to the UDP-glycosyltransferase family. Extended N-terminus.