Proteins encoded by v-myc and c-myc oncogenes: identification and localization in acute leukemia virus transformants and bursal lymphoma cell lines.

We have prepared an antiserum against a synthetic dodecapeptide whose sequence corresponds to the C terminus of the MC29 v-myc protein. This antiserum (anti-v-myc 12C) specifically precipitates the known gag-myc fusion proteins produced by the defective leukemia viruses MC29, CMII, and OK10, but does not react with gag-precursor or product proteins. In addition, proteins of 62 kd and 61/63 kd are precipitated by anti-v-myc 12C from OK10 and MH2 transformants, respectively. The serum also recognizes comigrating 62 kd proteins from three chicken bursal lymphoma cell lines and from the products of in vitro translation of c-myc-specific mRNA. All of these myc-related proteins are phosphorylated and all appear to be localized in the cell nucleus. In uninfected quail cells, anti-v-myc 12C also recognizes a candidate c-myc protein of 60 kd, which does not appear to be phosphorylated and is present in low levels relative to v-myc and lymphoma c-myc proteins.