Tyrosine phosphorylation of integrin beta3 regulates kindlin-2 binding and integrin activation.
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.
Bledzka
Kamila
K
Department of Molecular Cardiology, Joseph J Jacobs Center for Thrombosis and Vascular Biology, Cleveland Clinic, Cleveland, Ohio 44195, USA.
Bialkowska
Katarzyna
K
Nie
Huiqin
H
Qin
Jun
J
Byzova
Tatiana
T
Wu
Chuanyue
C
Plow
Edward F
EF
Ma
Yan-Qing
YQ
D020816:Amino Acid Motifs; D006801:Humans; D039661:Integrin beta3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014443:Tyrosine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C477322:FERMT3 protein, human; D039661:Integrin beta3; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D014443:Tyrosine