May play a role in CNS development by interacting with growth factors implicated in motor neuron differentiation and survival. May play a role in capillary formation and maintenance during angiogenesis. Modulates BMP activity by affecting its processing and delivery to the cell surface (By similarity). Interacts with BMP4 and BMP7. Expressed during embryonic development in brain, kidney, spinal chord, testis, lens, vibrissae, pinna, tooth primordia and in specific regions of the CNS. Expressed in adult lens. Displays male-specific expression in the fetal gonads with the strongest expression in the Sertoli cells of developing testis. Detected in embryo at 11.5 dpc to 17.7 dpc with a maximum between 12.5 and 13.5 dpc.