A 6-ARMED, TENASCIN-LIKE PROTEIN EXTRACTED FROM THE PORIFERA OSCARELLA-TUBERCULATA (HOMOSCLEROPHORIDA)

A six-armed complex could be extracted from the marine sponge Oscarell a tuberculata by a two-step incubation, first in Tris-buffered saline containing EDTA, then in Tris-buffered saline containing urea. The cru de extracts contained, in addition, collagen fibrils with surface fila ments, individual filaments resembling collagen molecules, and laminin /nidogen-like complexes. The extracts were subsequently purified by ge l-filtration chromatography and low-pressure ion-exchange chromatograp hy on DEAE-cellulose, then analyzed by SDS/PAGE and immunoblotting met hods. A glycoprotein of high molecular mass was isolated, and reduced to subunits of 230 kDa. After transfer to nitrocellulose, both the com plex and its subunits were faintly stained by antibodies against amphi bian tenascin. Electron microscopy of the purified extracts demonstrat ed the presence of a large population of tenascin-like molecules and c omplexes of several molecules interacting with each other by their cen tral globule.