Article

Tyrosine Phosphorylation of Integrin beta(3) Regulates Kindlin-2 Binding and Integrin Activation

Department of Molecular Cardiology, Joseph J Jacobs Center for Thrombosis and Vascular Biology, Cleveland Clinic, Cleveland, Ohio 44195, USA.
Journal of Biological Chemistry (Impact Factor: 4.6). 10/2010; 285(40):30370-4. DOI: 10.1074/jbc.C110.134247
Source: PubMed

ABSTRACT Kindlins are essential for integrin activation in cell systems and do so by working in a cooperative fashion with talin via their direct interaction with integrin β cytoplasmic tails (CTs). Kindlins interact with the membrane-distal NxxY motif, which is distinct from the talin-binding site within the membrane-proximal NxxY motif. The Tyr residues in both motifs can be phosphorylated, and it has been suggested that this modification of the membrane-proximal NxxY motif negatively regulates interaction with the talin head domain. However, the influence of Tyr phosphorylation of the membrane-distal NxxY motif on kindlin binding is unknown. Using mutational analyses and phosphorylated peptides, we show that phosphorylation of the membrane-distal NITY(759) motif in the β(3) CT disrupts kindlin-2 recognition. Phosphorylation of this membrane-distal Tyr also disables the ability of kindlin-2 to coactivate the integrin. In direct binding studies, peptides corresponding to the non-phosphorylated β(3) CT interacted well with kindlin-2, whereas the Tyr(759)-phosphorylated peptide failed to bind kindlin-2 with measurable affinity. These observations indicate that transitions between the phosphorylated and non-phosphorylated states of the integrin β(3) CT determine reactivity with kindlin-2 and govern the role of kindlin-2 in regulating integrin activation.

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