VERSICAN V-2 IS A MAJOR EXTRACELLULAR-MATRIX COMPONENT OF THE MATURE BOVINE BRAIN

We have isolated and characterized the proteoglycan isoforms of versic an from bovine brain extracts. Our approach included (i) cDNA cloning and sequencing of the entire open reading frame encoding the bovine ve rsican splice variants; (ii) preparation of antibodies against bovine versican using recombinant core protein fragments and synthetic peptid es; (iii) isolation of versican isoforms by ammonium sulfate precipita tion followed by anion exchange and hyaluronan affinity chromatography ; and (iv) characterization by SDS-polyacrylamide gel electrophoresis and Coomassie Blue staining or immunoblotting. Our results demonstrate that versican V-2 is, together with brevican, a major component of th e mature brain extracellular matrix. Versicans V-0 and V-1 are only pr esent in relatively small amounts. Versican V-2 migrates after chondro itinase ABC digestion with an apparent molecular mass of about 400 kDa , whereas it barely enters a 4-15% polyacrylamide gel without the enzy me treatment. The 400-kDa product is recognized by antibodies against the glycosaminoglycan-alpha domain and against synthetic NH2- and COOH -terminal peptides. Our preparations contain no major proteolytic prod ucts of versican, e.g, hyaluronectin or glial hyaluronate-binding prot ein. Having biochemical quantities of versican V-2 available will allo w us to test its putative modulatory role in neuronal cell adhesion an d axonal growth.