Journal of Cell Science 116, e603-e603 (2003)
Copyright © 2003 The Company of Biologists Limited
Focal adhesion phosphorylation dynamics
Focal adhesions (FAs) are multiprotein complexes that link integrins
attached to the extracellular matrix with the actin cytoskeleton. Assembly and
maintenance of these complexes is regulated by Rho family GTPases. Tyrosine
phosphorylation of FA proteins such as paxillin and focal adhesion kinase
(FAK) also seems to play a part. This provides docking sites for other
proteins (e.g. Src), but its role in regulation of FA assembly/turnover is
unclear. Benjamin Geiger and co-workers have therefore developed a novel
FA-phosphorylation assay, in which they use a construct comprising yellow
fluorescent protein and two phosphotyrosine-binding SH2 domains from Src
(YFP-dSH2) to monitor the appearance of phosphorylated tyrosine at FAs
dynamically in living cells (see p.
975). The authors observe that, following stimulation of SV80 cells
by the microtubule-depolymerizing drug nocodazole, vinculin, paxillin and FA
kinase (FAK) are rapidly recruited to growing FAs. Phosphotyrosine residues,
however, do not appear until a few minutes later. This indicates that tyrosine
phosphorylation is unlikely to drive focal adhesion formation but is a
secondary event that might instead be involved in FA turnover or
signalling.

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- Live-cell monitoring of tyrosine phosphorylation in focal adhesions following microtubule disruption
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JCS 2003 116: 975-986.
[Abstract]
[Full Text]