Purification and analysis of a human sarcoma associated antigen

S1, a heterophile antigen present on human sarcoma cell lines in culture, has been previously defined by this laboratory [1,2]. This antigen is also present in guinea-pig kidney. Purification of the antigen to homogeneity has now been achieved by a combination of ammonium sulfate fractionation, DEAE-cellulose, sephadex, high pressure liquid chromotography and affinity chromotography. S1 is a monomeric protein of 70 000 Da, as indicated by the presence of a single band on SDS-PAGE. Amino acid analysis demonstrates the prevalence of glycine, lysine and glutamic acid. Aspartic acid was found to be the N-terminal residue with further sequence of glycine-valine-alanine-glutamic acid (gly-val-ala-glut).