title: Intranuclear degradation of the transformation-inducing protein encoded by avian MC29 virus.
abstract: The nuclear protein, p110, encoded by the avian MC29 virus degrades with a half-life of 30 to 40 min in virus-transformed cells. Inhibitors of lysosomal proteolysis had no effect on this degradation. When inhibitors of RNA or protein synthesis were added immediately after pulse-labeling the p110 with [35S]methionine, degradation was impeded. Treatment of cells with cycloheximide prior to, and after, the pulse extended the half-life of p110 further than post-treatment alone, and addition of both actinomycin D and cycloheximide to cells pretreated with cycloheximide extended the half-life even further. In cells depleted of cellular ATP using a glucose-deficient medium containing oligomycin, degradation of p110 was only partially inhibited, indicating no direct involvement of ATP in degradation. Isolation of nuclei or nuclear matrices containing labeled p110, with subsequent incubation, resulted in minimal loss of p110 during several hours. These results suggest that p110 is degraded by a protease which is itself labile and freely diffusible from the nucleus, and, in addition, degradation may involve interaction of p110 with newly synthesized RNA.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002472:Cell Transformation, Viral; D003370:Coturnix; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000378:metabolism; D015683:Gene Products, gag; D005947:Glucose / Q000378:metabolism; D006207:Half-Life; D008715:Methionine / Q000378:metabolism; D012191:Retroviridae Proteins / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D015683:Gene Products, gag; D012191:Retroviridae Proteins; D014764:Viral Proteins; D003609:Dactinomycin; D000255:Adenosine Triphosphate; D003513:Cycloheximide; D008715:Methionine; D005947:Glucose