Abstract
Integrins are involved in cell migration and adhesion. A large number of proteins interact with the cytoplasmic tails of integrins. Dok1 is a negative regulator of integrin activation and it binds to the phosphorylated membrane proximal NxxY motif in a number of integrin β tails. The β tail of the β2 integrins contains a non-phosphorylatable NxxF motif. Hence it is unclear how Dok1 associates with the β2 integrins. We showed in this study using NMR and cell based analyses that residues Ser745 and Ser756 in the integrin β2 tail, which are adjacent to the NxxF motif, are required for Dok1 interaction. NMR analyses detected significant chemical shift changes and higher affinity interactions between Dok1 phospho-tyrosine binding (PTB) domain and integrin β2 tail peptide containing pSer756 compared to pSer745. The phosphorylated β2 peptide occupies the canonical ligand binding pocket of Dok1 based on the docked structure of the β2 tail-Dok1 PTB complex. Taken together, our data suggest an alternate phosphorylation switch in β2 integrins that regulates Dok1 binding. This could be important for cells of the immune system and their functions.
Highlights
Integrins are a large family of cell surface α β heterodimers that mediate cell-cell and cell-ECM interactions necessary for many physiological processes, including hemostasis, wound healing, immunity and developmental biology[1]
A series of 15N-1H HSQC spectra of 15N-labelled phospho-tyrosine binding (PTB) domain were acquired at various concentrations of integrin β 2 tail peptides (Fig. 1A,B). 15N-1H HSQC spectra of the PTB domain showed discernable chemical shift changes upon addition of phosphorylated integrin β 2 tail peptides
Interactions with cognate proteins can be modulated by phosphorylation of the integrin β tail at specific sequence motifs[12,13,28]
Summary
Integrins are a large family of cell surface α β heterodimers that mediate cell-cell and cell-ECM interactions necessary for many physiological processes, including hemostasis, wound healing, immunity and developmental biology[1]. The FERM domain lies in the head region of talin, and a phosphotyrosine binding (PTB) fold in its F3 subdomain has been shown to bind the membrane proximal NPLY747 motif of the integrin β 3 tail[7]. This form of interaction is not limited to talin because it extends to other cytoplasmic proteins containing PTB folds, including negative regulator of Notch signaling (Numb), downstream target of c-Abl (Dab) and docking protein 1 (Dok[1]; p62Dok)[8]. The current findings suggest a novel paradigm involving an alternative phosphorylation switch in the integrin β 2 tail that is required for the regulation of β 2 integrins by Dok[1]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
