Antiserum to purified fibronectin has been used to investigate transformation-associated heterogeneity in surface components antigenically related to fibronectin. Examination of extracts from surface-labeled rat cells by gradient gel electrophoresis revealed in “normal” cells the presence of two species with approximate molecular weights of 250,000 and 230,000, which were decreased in wild-type transformed cells. Reaction with antifibronectin serum revealed the selective precipitation of the two transformation-sensitive surface components.

A similar experiment with ts-NT3-KR that expresses a normal phenotype at 37° and a transformed morphology at 33° did not reveal a markedly altered surface labeling pattern at both temperatures. However, reaction with antifibronectin serum did show a weak but detectable recognition of a 230,000-dalton doublet in the cells grown at 37°, and immune precipitation of components in the 100,000- and 60,000-dalton region in cells grown at 33°. Experiments with normal mouse cells revealed a different ratio of two fibronectin-related external proteins with similar molecular weights to those seen in normal rat cells.

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Supported in part by CONICIT (Venezuela) under Grant 31.26.S1-0469.

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