PERLECAN AND BASEMENT MEMBRANE CHONDROITIN SULFATE PROTEOGLYCAN (BAMACAN) ARE 2 BASEMENT MEMBRANE CHONDROITIN DERMATAN SULFATE PROTEOGLYCANS IN THE ENGELBRETH-HOLM-SWARM TUMOR MATRIX

The presence of proteoglycans bearing galactosaminoglycan chains has b een reported, but none has been identified previously in the matrix of the Engelbreth-Holm-Swarm tumor, which is a source of several basemen t membrane components, This tumor matrix contains perlecan, a large, l ow buoyant density heparan sulfate proteoglycan, widespread in many ba sement membranes and connective tissues. We now identify two distinct proteoglycan species from this tumor source, which are substituted wit h galactosaminoglycans and which show basement membrane localization b y immunohistochemistry. One species is perlecan but, in addition to be ing present as a heparan sulfate proteoglycan, it is also present as a hybrid molecule, with dermatan sulfate chains, A minor population of perlecan apparently lacks heparan sulfate chains totally, and some of this is substituted with chondroitin sulfate, The second species is im munologically related to basement membrane-chondroitin sulfate proteog lycan (BM-CSPG) and bears chondroitin sulfate chains. No BM-CSPG was d etectable which was substituted with heparan sulfate chains. A combina tion of immunological and molecular approaches, including cDNA cloning , showed that perlecan and BM-CSPG are distinct in core protein struct ure. Both are, however, basement membrane components, although there a re tissue-specific differences in their distribution.