Is there a role for actin in virus budding?
Electrophoretic data from both sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE) and acid-urea gels reveal a protein in purified murine mammary tumor virus (MuMTV) which co-migrates with purified chick skeletal muscle actin. 125I-labeling of intact and disrupted virus preparations shows that the actin-like protein is not artifactually adsorbed to the outside of virions during isolation. Quantitative SDS-PAGE and examination of negatively stained preparations show that the actin cannot be accounted for by a contaminating population of virus-free vesicles. The ultrastructure of mammary epithelial cells and of Rous sarcoma virus-transformed chick embryo fibroblasts shows that virus extrusion is associated with filament-containing cellular processes. In particular, MuMTV is released from the ends of long microvilli which contain a bundle of 6-8-nm microfilaments and share other structural features with intestinal microvilli. We suggest that virus nucleoids require an interaction with host cell contractile proteins for their extrusion from the cell.
D000199:Actins / Q000302:isolation & purification / Q000502:physiology*; D000818:Animals; D002645:Chickens; D005260:Female; D007774:Lactation; D008325:Mammary Neoplasms, Experimental / Q000382:microbiology; D008324:Mammary Tumor Virus, Mouse / Q000254:growth & development* / Q000302:isolation & purification / Q000648:ultrastructure; D051379:Mice; D008854:Microscopy, Electron; D008892:Milk / Q000382:microbiology; D009132:Muscles / Q000032:analysis; D011247:Pregnancy
D000199:Actins