A membrane glycoprotein involved in teratocarcinoma cell adhesion to substratum

Abstract

An antiserum was raised against glycoproteins isolated from teratocarcinoma OTT6050 by affinity chromatography on Ricinus communis agglutinin-1 (RCA-1). The antiserum inhibited attachment and spreading of the teratocarcinoma cells on plastic tissue culture plates. Embryonal carcinoma cells (F9 and N4-1) and PYS-2 parietal endodermal cells were also affected. The antiserum was also effective in preventing adhesion of trophoblasts to substratum. Furthermore, the antiserum caused rounding and detachment of the cells previously spread on the substrates, and the process could be reversed by removing the antiserum. Fab fragments isolated from the antiserum also inhibited cell-substratum adhesion, but not cell-cell adhesion, indicating that the factor involved is specific for cell-substratum adhesion. The antiserum inhibited adhesion of F9 and PYS-2 cells not only to plastic dishes but also to those coated with plasma fibronectin, laminin, and plant lectins such as concanavalin A (conA). Therefore, it is likely that the antiserum inhibited cell-substratum adhesion by blocking the function of an intrinsic component of cell-substratum adhesion rather than interfering with specific receptors for fibronectin or laminin. The glycoprotein with the antibody-blocking activity was partially purified from particulate fraction of teratocarcinoma OTT6050 by extraction with Triton X-100 and affinity chromatography on RCA-1-agarose and conA-agarose Upon Western blot analysis of the glycoprotein preparation, the antibody reacted only with a glycoprotein of the apparent molecular weight (MW), 125 000 (GP-125). An antibody preparation was isolated by affinity chromatography on Sepharose 4B coupled with the glycoprotein fraction and was shown to have all of the activities described above. Molecules resembling GP-125 could be also isolated from cultured F9 and PYS-2 cells by solubilization with Triton X-100 and indirect immunoprecipitation.