Probable UDP-L-arabinose mutase involved in the biosynthesis of cell wall non-cellulosic polysaccharides (By similarity). Was initially shown to possess an autoglycosylating activity which is dependent on the presence of UDP-glucose and manganese (PubMed:9207152). UDP-beta-L-arabinofuranose = UDP-beta-L-arabinopyranose Inhibited by inhibitor protein (IP) which may be a form of sucrose synthase. Homopentamer or homohexamer. Cell wall-associated, with highest concentrations on plasmodesmata. Also located in the Golgi apparatus. The conserved DXD motif is involved in enzyme activity. Reversibly glycosylated by UDP-glucose, UDP-xylose and UDP-galactose, but not UDP-mannose. Belongs to the RGP family.