A NEW HEPARAN-SULFATE PROTEOGLYCAN IN THE EXTRACELLULAR-MATRIX OF THEDEVELOPING CHICK-EMBRYO

A new heparan sulfate proteoglycan was identified by two monoclonal an tibodies. The antibodies (hybridoma clones 6C4 and 1B11) were generate d from mice immunized with inner limiting membranes of the embryonic c hick retina. The proteoglycan had an apparent molecular weight of 250 kDa with a core protein of 180 kDa, Antibodies to perlecan and to a re cently identified brain-derived heparan sulfate proteoglycan did not c ross-react with purified 6C4/1B11 antigen, confirming that the three p roteoglycans are not related. The 6C4/1B11 proteoglycan was abundant i n basal laminae, such as the inner limiting membrane of the retina, th e lens capsule, the epidermal, the pial, and the muscle basal laminae, and the vitreous body. The distribution and developmental expression of the 6C4/1B11 proteoglycan was different than that of perlecan and t he brain-derived heparan sulfate proteoglycan. When used as a substrat e for embryonic retinal explants, the proteoglycan did not support axo nal outgrowth in vitro. The data present a new heparan sulfate proteog lycan and demonstrate the existence of at least three different hepara n sulfate proteoglycans in the developing chick embryo with partially overlapping distribution. (C) 1994 Academic Press, Inc.