label: alpha-D-galacturonosyl-[(1->2)-alpha-L-rhamnosyl-(1->4)-alpha-D-galacturonosyl](n) + UDP-beta-L-rhamnose => [(1->2)-alpha-L-rhamnosyl-(1->4)-alpha-D-galacturonosyl](n+1) + UDP + H(+)
label_lc: alpha-d-galacturonosyl-[(1->2)-alpha-l-rhamnosyl-(1->4)-alpha-d-galacturonosyl](n) + udp-beta-l-rhamnose => [(1->2)-alpha-l-rhamnosyl-(1->4)-alpha-d-galacturonosyl](n+1) + udp + h(+)