1 research outputs found
EGF Regulates the Interaction of Tks4 with Src through Its SH2 and SH3 Domains
The
nonreceptor tyrosine kinase Src is a central component of the
epidermal growth factor (EGF) signaling pathway. Our group recently
showed that the Frank-ter Haar syndrome protein Tks4 (tyrosine kinase
substrate with four Src homology 3 domains) is also involved in EGF
signaling. Here we demonstrate that Tks4 and Src bind directly to
each other and elucidate the details of the molecular mechanism of
this complex formation. Results of GST pull-down and fluorescence
polarization assays show that both a proline-rich SH3 binding motif
(PSRPLPDAP, residues 466–474) and an adjacent phosphotyrosine-containing
SH2 binding motif (pYEEI, residues 508–511) in Tks4 are responsible
for Src binding. These motifs interact with the SH3 and SH2 domains
of Src, respectively, leading to a synergistic enhancement of binding
strength and a highly stable, “bidentate”-type of interaction.
In agreement with these results, we found that the association of
Src with Tks4 is permanent and the complex lasts at least 3 h in living
cells. We conclude that the interaction of Tks4 with Src may result
in the long term stabilization of the kinase in its active conformation,
leading to prolonged Src activity following EGF stimulation