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Association of the Tyrosine Phosphatase SHP‐2 with Transducin‐α and a 97‐kDa Tyrosine‐Phosphorylated Protein in Photoreceptor Rod Outer Segments
Author(s) -
Bell Michael W.,
Alvarez Kathy,
Ghalayini Abboud J.
Publication year - 1999
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1999.0732331.x
Subject(s) - protein tyrosine phosphatase , tyrosine phosphorylation , transducin , phosphorylation , tyrosine , microbiology and biotechnology , biology , biochemistry , sh2 domain , signal transduction , g protein
: Increasing evidence indicates that tyrosine phosphorylation, controlled by the concerted action of tyrosine kinases and protein tyrosine phosphatases (PTPs), plays important roles in retinal photoreceptor rod outer segments (ROS). We characterized PTP activity in isolated bovine ROS that is significantly inhibited by orthovanadate. Incubating ROS in the presence of exogenous Mg 2+ , ATP, and orthovanadate dramatically enhanced the tyrosine phosphorylation of several endogenous proteins. SHP‐2, a PTP with two SH2 domains, was identified in ROS by immunoblot analysis and was found to associate with ROS membranes. Immunocytochemisry showed localization of SHP‐2 in photoreceptor outer segments and possibly in the outer plexiform, inner nuclear, and inner plexiform cell layers of the retina as well. SHP‐2 associated with transducin‐α and a 97‐kDa tyrosine‐phosphorylated protein in ROS, suggesting the formation of a multimeric signaling complex. Based on its association with transducin‐α and a 97‐kDa protein, SHP‐2 may regulate the tyrosine phosphorylation of endogenous proteins, including transducin‐α, and may play a significant role in a novel signaling pathway in photoreceptors.