Proteoglycan that seems to be implicated in diverse developmental roles such as differentiation, cell-cell recognition, embryogenesis and programmed cell death (Probable). Involved in the regulation of root hair elongation (PubMed:21248074). Contains 4-hydroxyproline; hydroxylated on Pro-32, Pro-34 and Pro-36. O-glycosylated on hydroxyprolines; noncontiguous hydroxylproline residues are glycosylated with arabinogalactan. Formation of abnormal long root hairs. Belongs to the AG-peptide AGP family.