The physical interactions between p37env-mos and tubulin structures.
The c-mos protein has been reported to be complexed with tubulin and to co-localize with microtubules in unfertilized Xenopus eggs as well as in NIH3T3 cells transformed by the Xenopus c-mos gene. We performed experiments to determine whether the viral mos protein, p37v-mos, also associates with tubulin. Both mouse c-mos and v-mos proteins synthesized in vitro co-polymerized with tubulin. Upon incubation at 37 degrees C, essentially all of the mos protein (both viral and cellular) co-polymerized with tubulin, while more than 50% of the tubulin remained in the depolymerized state. The mos-tubulin interaction was specific, as indicated by the insolubility of the v-mos protein following a second cycle of temperature-dependent depolymerization/polymerization. Beta-tubulin was shown to co-precipitate with p37v-mos and to be phosphorylated by the mos kinase in vitro. Although both v-mos and c-mos proteins co-polymerize with tubulin, p37v-mos behaved differently from p39c-mos on gel filtration columns under conditions that favor disassembly of microtubules. Like Xenopus c-mos, the bulk of the mouse c-mos protein synthesized in vitro appeared in structures that fractionate at about 500 kDa. In contrast to c-mos, the majority of the v-mos protein, either isolated from stably transformed NIH3T3 cells or synthesized in vitro, eluted in the 100 kDa fraction, co-fractionating with tubulin dimers. Therefore, the v-mos protein appears to have a higher affinity for unpolymerized tubulin than c-mos, under conditions that favor disassembly of microtubules.
Bai
W
W
Department of Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Singh
B
B
Yang
Y
Y
Ramagli
L S
LS
Nash
M
M
Herzog
N K
NK
Arlinghaus
R B
RB
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D016258:Genes, mos; D051379:Mice; D008969:Molecular Sequence Data; D017232:Oncogene Proteins v-mos; D010766:Phosphorylation; D011108:Polymers; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D017231:Proto-Oncogene Proteins c-mos; D015682:Retroviridae Proteins, Oncogenic / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism*; D014760:Viral Fusion Proteins / Q000378:metabolism
D017232:Oncogene Proteins v-mos; D011108:Polymers; D011518:Proto-Oncogene Proteins; D015682:Retroviridae Proteins, Oncogenic; D014404:Tubulin; D014760:Viral Fusion Proteins; D017231:Proto-Oncogene Proteins c-mos