Arabinosylated glycopeptide hormones: new insights into CLAVATA3 structure

Secreted peptides are now recognized as important members of hormones that coordinate and specify cellular functions in plants. Recent accumulating evidence shows that secreted peptide hormones are often post-translationally modified, and such modification is critical for their function. In this review, we highlight hydroxyproline arabinosylation, which has been found in several peptide hormones including CLAVATA3 (CLV3), a key peptide controlling stem cell renewal and differentiation in Arabidopsis shoot apical meristem. Arabinosylation of CLV3 is important for its biological activity and for high-affinity binding to its receptor, CLV1. We discuss the physiological functions of known glycopeptide hormones, the structural information on sugar chains, and possible mechanisms of glycosylation.