The presence of proteoglycans bearing galactosaminoglycan chains has been reported, but none has been identified previously in the matrix of the Engelbreth-Holm-Swarm tumor, which is a source of several basement membrane components. This tumor matrix contains perlecan, a large, low buoyant density heparan sulfate proteoglycan, widespread in many basement membranes and connective tissues. We now identify two distinct proteoglycan species from this tumor source, which are substituted with galactosaminoglycans and which show basement membrane localization by immunohistochemistry. One species is perlecan but, in addition to being 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 immunologically related to basement membrane-chondroitin sulfate proteoglycan (BM-CSPG) and bears chondroitin sulfate chains. No BM-CSPG was detectable which was substituted with heparan sulfate chains. A combination of immunological and molecular approaches, including cDNA cloning, showed that perlecan and BM-CSPG are distinct in core protein structure. Both are, however, basement membrane components, although there are tissue-specific differences in their distribution.
Keywords: Animals; Antibodies; Antibodies, Monoclonal; Basement Membrane; Blotting, Western; Cloning, Molecular; DNA, Complementary; Fluorescent Antibody Technique, Indirect; Heparan Sulfate Proteoglycans; Heparitin Sulfate; Humans; Immunohistochemistry; Kidney Cortex; Mice; Neoplasms, Experimental; Proteochondroitin Sulfates; Proteoglycans; Rabbits; Rats; Recombinant Fusion Proteins; Skin