Proteoglycan that seems to be implicated in diverse developmental roles such as differentiation, cell-cell recognition, embryogenesis and programmed cell death. Up-regulated by AHL16/TEK. Contains 4-hydroxyproline; hydroxylated on Pro-28, Pro-30 and Pro-32. O-glycosylated on hydroxyprolines; noncontiguous hydroxylproline residues are glycosylated with arabinogalactan. Belongs to the AG-peptide AGP family. Extended C-terminus.