Multiple antigens recognized by anti-c-myc antibodies in human cells and Xenopus oocytes.

We have investigated the localization, solubility, serum regulation, and phosphorylation of MYC antigens from Colo 320 cells, a human transformed cell line with an amplified c-myc gene, and from Xenopus oocytes, which express high levels of c-myc mRNA. Although MYC proteins are often reported to range from 60 to 68 kilodaltons, our panel of anti-MYC monoclonal antibodies recognized a number of higher and lower molecular mass antigens, in addition to proteins within this range. Based upon various criteria, including cross-recognition by several anti-MYC antibodies, we suggest that some of these antigens are bona fide MYC family proteins. Our results, as well as those of others reported previously, suggest that several MYC antigens may be simultaneously present in cells. The apparent diversity among members of the MYC family of antigens raises the possibility of multiple cellular functions and regulatory roles for these proteins.