Immunological characterization of the low-molecular-weight dna binding protein of mouse mammary tumor virus

Abstract

P14, a low‐molecular‐weight MMTV protein previously identified as having DNA‐binding properties and encoded by the gag region of the MMTV genome, was purified by affinity chromatography on DNA‐sepharose. Immunological characterization of the purified protein showed that MMTV p14 shares no cross‐reactivity with gp52, gp36 and p10, antigens associated with the MMTV envelope, nor with p27 antigen found in the virion core. Purified MMTV p14 did show cross‐reactivity with purified intracytoplasmic A particles, supporting the concept that A particles are morphological precursors to MMTV cores. In addition, shared antigenic determinants between intracytoplasmic A particles and MMTV p27, p20 and p10 were demonstrated. MMTV p14 did not cross‐react with the low‐molecular‐weight DNA‐binding proteins of MuLV or of type‐C or ‐D viruses of higher mammals.