Human brain tissue from cerebellum and hippocampus was obtained between 2 h and 24 h post mortem and, after extraction in the presence of proteinase inhibitors, proteoglycans were purified by anion-exchange chromatography. The versican component was characterized by Western analysis with antibodies to the N-terminal peptide (LF99), the N-terminal globular domain (12C5) and the two GAG (glycosaminoglycan) attachment regions (anti-GAG-alpha and anti-GAG-beta). The results indicated that versican V2 is the major variant in all brain samples, and that it exists as the full-length form and also as at least six C-terminally truncated forms. The major immunoreactive species present is a 64 kDa product, which we identified by biochemical and immunological analysis as the brain protein previously termed GHAP (glial hyaluronate binding protein) [Perides, Lane, Andrews, Dahl and Bignami (1989) J. Biol. Chem. 264, 5981-5987]. Immunological analysis of purified human GHAP using a new anti-neoepitope antiserum (JSCNIV) showed that its C-terminal sequence is NIVSFE(405), and digestion of human cerebellum proteoglycans with ADAMTS4 (aggrecanase-1, where ADAMTS, a disintegrin and metalloproteinase with thrombospondin-1-like motifs) indicated that GHAP is a product of cleavage of versican V0 or V2 at the Glu(405)-Gln(406) bond. Since human cerebellum extracts contained multiple forms of ADAMTS4 protein on Western analysis, these data suggest that one or more members of the 'aggrecanase' group of the ADAMTS family (ADAMTS 1, 4, 5 and 9) are responsible for turnover of versican V2 in the adult human brain.