Maller, James L. and Foulkes, J. Gordon and Erikson, Eleanor and Baltimore, David (1985) Phosphorylation of Ribosomal Protein S6 on Serine after Microinjection of the Abelson Murine Leukemia Virus Tyrosine-Specific Protein Kinase into Xenopus oocytes. Proceedings of the National Academy of Sciences of the United States of America, 82 (2). pp. 272-276. ISSN 0027-8424 http://resolver.caltech.edu/CaltechAUTHORS:MALpnas85
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Phosphorylation of ribosomal protein S6 in NIH 3T3 fibroblasts is dependent on the presence of serum, but after transformation of these cells by Abelson murine leukemia virus (Ab-MuLV), S6 remained highly phosphorylated on serine residues either in the absence or the presence of serum. To investigate whether S6 phosphorylation in this system was a consequence of the action of the Ab-MuLV tyrosine-specific protein kinase, purified Ab-MuLV kinase made in Escherichia coli was microinjected into Xenopus oocytes and was observed to cause a 7- to 15-fold increase in the phosphorylation of S6 on serine residues. Two-dimensional phosphopeptide maps of S6 phosphorylated in Ab-MuLV-transformed NIH cells in the absence of serum were identical to those of S6 isolated from normal cells grown in the presence of serum. In addition, S6 from oocytes injected with Ab-MuLV kinase yielded an S6 phosphopeptide map indistinguishable from that of serum-stimulated NIH 3T3 cells, whereas S6 from control oocytes lacked several phosphopeptides. Ab-MuLV kinase did not phosphorylate S6 directly in vitro, and microinjection of a mutant Ab-MuLV protein lacking kinase activity had no effect. These results indicate that the Ab-MuLV kinase interacts with a cellular pathway to enhance S6 phosphorylation by directly or indirectly activating an S6 protein kinase and/or inactivating an S6 protein phosphatase.
|Additional Information:||Copyright © 1985 by the National Academy of Sciences Contributed by David Baltimore, August 29, 1984 This work was supported by grants from the National Institutes of Health (AM28353 to J.L.M. and CA26717 to D.B.) and by a grant from the American Cancer Society (CD-187) to J.L.M., who is an Established Investigator of the American Heart Association. Part of this work was carried out while J.G.F. was a recipient of a Medical Research Council (U.K.) Travel Fellowship. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.|
|Subject Keywords:||tyrosyl-protein kinases; growth control|
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|Deposited By:||Archive Administrator|
|Deposited On:||02 Jan 2007|
|Last Modified:||26 Dec 2012 09:26|
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