galactose/rhamnose binding lectin domain found in plant beta-galactosidases and similar proteins
The family represents a group of plant beta-galactosidases (BGals), which belong to glycoside hydrolase family 35. They have a C-terminal domain homologous to animal galactose and rhamnose-binding lectins. BGals (EC 3.2.1.23), also called Exo-(1->4)-beta-D-galactanase, or lactase, catalyze hydrolysis of terminal non-reducing beta-D-galactose residues in beta-D-galactosides. Some family members contain more than one galactose/rhamnose binding lectin domain. Due to the lack of rhamnose-binding key residues, the galactose/rhamnose-binding lectin domains of BGals do not form a binding pocket for rhamnose. Therefore, BGals are unlikely to act as rhamnose-binding lectins.
Jiyao W et al.(2023). "The conserved domain database in 2023.",