Transfer of a beta-galactosyl residue in a beta-(1->4) linkage from UDP-alpha-D-galactose to rhamnosyl residues within the rhamnogalacturonan I backbone.
Comment
The enzyme, characterized from the plant Vigna angularis (azuki beans), participates in the biosynthesis of rhamnogalacturonan I, one of the components of pectin in plant cell wall. It does not require any metal ions, and prefers substrates with a degree of polymerization larger than 9.
