title: Immunocolloidal gold electron microscopy of viral antigens and cellular actin in C3H/He mouse mammary tumors.
abstract: Mouse mammary tumor virus (MMTV) antigens and cellular actin were visualized with Protein A-coated colloidal gold at the ultrastructural level in C3H/He mouse mammary tumors using various antisera. Observations with the postembedding method and statistical analyses of these data showed: (a) a glycoprotein with a molecular weight of 52,000 resided on the envelope of mature virions (B-particles), on the surface of budding particles, and on the vacuolar membrane, but not on intracytoplasmic A-particles (A-particles); (b) B-particle antigens were shared by A-, B-, and budding particles with more reacting gold particles on B-particles; and (c) a protein with a molecular weight of 27,000, p27 and A-particle antigens were also shared equally by all MMTV-related particles with preferential localization on the nucleoid of B-particles and the double ring of A-particles. All of these observations are consistent with and further confirm the proposal that A-particles are pronucleocapsids of MMTV. Cellular actin was concentrated in the outermost thin cytoplasmic layer and in microvilli. Single gold particles were also found on budding and B-particles implying that actin plays a role in the MMTV budding process.
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D000956:Antigens, Viral / Q000032:analysis*; D002213:Capsid / Q000276:immunology; D005260:Female; D006046:Gold; D007181:Inclusion Bodies, Viral / Q000276:immunology*; D008325:Mammary Neoplasms, Experimental / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D051379:Mice; D008854:Microscopy, Electron / Q000379:methods; D012191:Retroviridae Proteins / Q000276:immunology / Q000378:metabolism; D014758:Viral Core Proteins / Q000276:immunology; D014759:Viral Envelope Proteins / Q000276:immunology / Q000378:metabolism; D014779:Virus Replication
chemical_list: D000199:Actins; D000956:Antigens, Viral; D012191:Retroviridae Proteins; D014758:Viral Core Proteins; D014759:Viral Envelope Proteins; D006046:Gold