Proteoglycan that seems to be implicated in diverse developmental roles such as differentiation, cell-cell recognition, embryogenesis and programmed cell death. Expressed in pollen grains. Up-regulated by AHL16/TEK. Contains 4-hydroxyproline; hydroxylated on Pro-29, Pro-31 and Pro-33. O-glycosylated on hydroxyprolines; noncontiguous hydroxylproline residues are glycosylated with arabinogalactan. Belongs to the AG-peptide AGP family.