an anthocyanidin 3-O-beta-D-sambubioside + UDP + 2 H(+) => an anthocyanidin 3-O-beta-D-glucoside + UDP-alpha-D-xylose
an anthocyanidin 3-o-beta-d-sambubioside + udp + 2 h(+) => an anthocyanidin 3-o-beta-d-glucoside + udp-alpha-d-xylose