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Mol. Cell. Biol., 01 1998, 250-259, Vol 18, No. 1
F Liu, MA Sells and J Chernoff
We have recently shown that protein tyrosine phosphatase 1B (PTP1B)
associates with the docking protein p130Cas in 3Y1 rat fibroblasts. This
interaction is mediated by a proline-rich sequence on PTP1B and the SH3
domain on p130Cas. Expression of wild-type PTP1B (WT-PTP1B), but not a
catalytically competent, proline-to-alanine point mutant that cannot bind
p130Cas (PA-PTP1B), causes substantial tyrosine dephosphorylation of
p130Cas (F. Liu, D. E. Hill, and J. Chernoff, J. Biol. Chem.
271:31290-31295, 1996). Here we demonstrate that WT-, but not PA-PTP1B,
inhibits transformation of rat 3Y1 fibroblasts by v-crk, - src, and -ras,
but not by v-raf. These effects on transformation correlate with the
phosphorylation status of p130Cas and two proteins that are associated with
p130Cas, Paxillin and Fak. Expression of WT- PTP1B reduces formation of
p130Cas-Crk complexes and inhibits mitogen- activated protein kinase
activation by Src and Crk. These data show that transformation suppression
by PTP1B requires a functional SH3 ligand and suggest that p130Cas may
represent an important physiological target of PTP1B in cells.
Copyright © 1998, American Society for Microbiology
Transformation suppression by protein tyrosine phosphatase 1B requires a functional SH3 ligand
Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
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