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Properties of the intracytoplasmic A particles purified from mouse tumors

1972; Elsevier BV; Volume: 49; Issue: 1 Linguagem: Inglês

10.1016/s0042-6822(72)80007-2

1096-0341

Harutaka Tanaka, Akira Tamura, Daijiro Tsujimura,

Immune Cell Function and Interaction

A procedure for the isolation and purification of the intracytoplasmic A particles from lymphoid leukemias and mammary tumors of DBA/2 strain mice is described. The purified A particles are 71 nm in size, consist of a 10 nm thick shell and a core, have a buoyant density of 1.26 to 1.27, and contain about 9% RNA and protein but no DNA and lipid. Two antigens of mouse mammary tumor virus (MTV) are distinguished; one (MTV-a) is shared by the B particles of MTV and the intracytoplasmic A particles, but not by the intracisternal A particles of mouse myelomas or the C particles of Moloney sarcoma virus, thus clearly establishing that the intracytoplasmic A particles are immature forms of MTV. MTV-a is not soluble in its native state, and is shared by MTV of all mouse strains tested. It is single in the A particles but splits into two components of different antigenicites (a1 and a2) in the B particles. The other antigen (MTV-b) is an envelope antigen of the B particles. This is also found in mammary tumor extracts of all MTV-carrying mouse strains tested. MTV-b is easily destroyed by dithiothreitol. Comparison is made between these antigens and those reported already for MTV, and the natural distribution of the antigens in various forms of MTV in mouse tissues is discussed.