Characterization of activated and normal mouse Mos gene in murine 3T3 cells
Paules, R.S.; Resnick, J.; Kasenally, A.B.; Ernst, M.K.; Donovan, P.; Vande Woude, G.F.
Oncogene 7(12): 2489-2498
1992
ISSN/ISBN: 0950-9232 PMID: 1461652 Document Number: 403923
We have characterized the mouse Mos proto-oncogene product, pp39-Mos, in murine fibroblasts. When expressed in NIH3T3 cells under the influence of the long terminal repeat regulatory element from Moloney murine sarcoma virus (NIH(pTS-1) cells), the Mos protein was present in low levels and had a half-life of about 30 min. In extracts from NIH(pTS-1) cells, we detected additional forms of Mos protein that apparently arose from internal initiation codons (p24-Mos and p29-Mos) or from upstream non-AUG initiation codons (p42-Mos and p44-Mos). The Mos protein was found to exist in these cells as a phosphoprotein, pp39-Mos, and, when immunoprecipitated with an antiserum specific for the Mos N-terminus (anti-Mos(6-24)), had autophosphorylating kinase activity. We found that anti-Mos(6-24) also detected non-Mos protein kinase activity and non-Mos phosphoproteins in addition to p39-Mos. We present evidence, on both the RNA and protein levels, that non-transformed mouse 3T3 cells do not express endogenous Mos.