Fashena, Sarah J. and Zinn, Kai (1997) Transmembrane glycoprotein gp150 is a substrate for receptor tyrosine phosphatase DPTP10D in Drosophila cells. Molecular and Cellular Biology, 17 (12). pp. 6859-6867. ISSN 0270-7306 http://resolver.caltech.edu/CaltechAUTHORS:FASmcb97
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We have begun to explore the downstream signaling pathways of receptor protein tyrosine phosphatases (RPTPs) that control axon guidance decisions in the Drosophila central nervous system. We have focused our studies on the adhesion molecule-like gp150 protein, which binds directly to and is an in vitro substrate for the RPTP DPTP10D. Here we show that gp150 and DPTP10D form stable complexes in Drosophila Schneider 2 (S2) cells and in wild-type larval tissue. We also demonstrate that the DPTP10D cytoplasmic domain is sufficient to confer binding to gp150. gp150 has a short cytoplasmic domain containing four tyrosines, all found within sequences similar to immunoreceptor family tyrosine-based activation motifs (ITAMs). We demonstrate that gp150 is tyrosine phosphorylated in wild-type larvae. In S2 cells, gp150 becomes tyrosine phosphorylated following incubation with PTP inhibitors or upon coexpression of the Dsrc tyrosine kinase. Phosphorylated Dsrc and an unknown 40-kDa phosphoprotein form stable complexes with gp150, thereby implicating them in a putative gp150 signaling pathway. When coexpressed with gp150, either full-length DPTP10D or its cytoplasmic domain mediates gp150 dephosphorylation whereas a catalytically inactive DPTP10D cytoplasmic domain does not. The neural RPTP DPTP99A can also induce gp150 dephosphorylation but does not coimmunoprecipitate with gp150. Taken together, the results suggest that gp150 transduces signals via phosphorylation of its ITAM-like elements. Phosphotyrosines on gp150 might function as binding sites for downstream signaling molecules, thereby initiating a signaling cascade that could be modulated in vivo by RPTPs such as DPTP10D.
|Additional Information:||Copyright © 1997, American Society for Microbiology Received 9 May 1997/Returned for modification 2 July 1997/Accepted 9 September 1997 We thank Anya N. Varshavsky for excellent technical assistance; Qi Sun and Genya Popova for help in screening gp150 MAb supernatants; Shin-Shay Tian for providing the DPTP10D and DPTP99A expression plasmids; Steven Dodson, Ronald Herbst, and Michael Simon (Stanford University) for providing the Dsrc and Drk antibodies; Alan Comer (Hoffmann Laboratory, University of Wisconsin Medical School) for providing the Drosophila tyrosine kinase constructs; Sami Bahri and Bill Chia for providing the UAS-10D line; and Venus Ka-Man Lai (Pawson Laboratory, Mount Sinai Hospital, Toronto, Canada) for providing Dshc antisera and for innumerable discussions. We also thank Thomas Coleman, Jonathan Chernoff, and Erica Golemis (Fox Chase Cancer Research Center, Philadelphia, Pa.) and Kaushiki Menon (California Institute of Technology, Pasadena, Calif.) for reviewing the manuscript. This work was supported by NIH RO1 grant NS28182 to K.Z. Support for S.J.F. was provided by NIH training grant NS07251 and American Cancer Society Postdoctoral Fellowship PF-3988.|
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|Deposited On:||20 Oct 2006|
|Last Modified:||26 Dec 2012 09:13|
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