Immunogenic properties of soluble cytosol fractions on Meth A sarcoma cells

Tumor-associated transplantation antigen (TATA) was found to be present in fractions derived from the cytosol of the Meth A cell. Meth A ascites cells were disrupted nuclei and membranes were removed by low- and high-speed centrifugation, and the soluble protein was fractionated by ammonium sulfate precipitation and gel filtration chromatography. The TATA of the soluble cytosol fractions appears to be identical with the TATA solubilized from plasma membranes. The TATA of the cytosol fractions was found to be associated with proteins of an approximate apparent molecular weight of 60,000, specific for the Meth A tumor, and as immunogenic as the membrane-derived TATA. In addition, the most enriched TATA cytosol fraction shows inhibition of an antiserum capable of detecting a tumor-specific surface antigen of Meth A. These results suggest that Meth A TATA is not an integral membrane protein and may be related to the tumor-specific surface antigen detected serologically.