Collagen Cell Attachment Protein from Rat Hepatoma Cells1

This paper describes the isolation and partial characteriza tion of a collagen cell attachment protein from the spent culture medium of rat hepatoma cells. When compared with serum fibronectin, this attachment protein differed in several biochem ical parameters. The hepatoma attachment protein was partially purified by adsorbing and eluting from an inorganic gel, mag nesium oxide. Cell adhesive activity was routinely recovered at levels of 10 to 30%, and a 2000-fold purification was attained. The hepatoma attachment protein was shown to be sensitive to trypsin and chymotrypsin, to be heat inactivated at 61°, to have a molecular weight of 58,000, to have an isoelectric point of 4.1, to show an electrophoretic mobility on cellulose acetate of approximately one-half that of fibronectin, and not to crossreact with antifibronectin antisera.