Differences in the surface components of normal and SV-40 transformed 3T3 mouse fibroblasts

The differences in the surface components of 3T3 mouse fibroblasts and those transformed by Simian virus 40 have been examined using the isoelectric equilibrium method. The net negative surface charge density of the transformed cells appears to be marginally lower than that of the untransformed cell. Chemical modification studies of the surface groups have indicated that about 30% more cationic groups are present on the transformed cells, suggesting the occurrence of some additional basic material not detectable on the surface of normal cells. These basic groups show a modulation of ionisation characteristics in the presence of carboxylic groups. This may indicate a distribution of the cationic extra material in the vicinity of acidic glycoprotein components of the surface. This investigation has also revealed the occurrence of unidentified anionic groups which ionise at high pH, which appear to be thiol groups.