INSTITUTO DE CIENCIAS FISICAS
Unidad Ejecutora - UE
Protein tyrosine phosphatase 1B, PTP1B, targets fak and paxillin in cell-matrix adhesions
MARIA E. PEREZ COLLADO; CARLOS O. ARREGUI; ANGELA GONZALEZ; IGNACIO J. GENERAL; ANA GONZALEZ WUSENER; MELINA R. MAZA
JOURNAL OF CELL SCIENCE
COMPANY OF BIOLOGISTS LTD
Protein tyrosine phosphatase 1B (PTP1B) is an established regulator of cell-matrix adhesion and motility. However, the nature of substrate targets at adhesion sites remains to be validated. Here we used Bimolecular Fluorescence Complementation (BiFC) assays in combination with a substrate trapping mutant of PTP1B to directly examine whether relevant phosphotyrosines on paxillin and FAK are substrates of the phosphatase in the context of cell-matrix adhesion sites. We find that formation of catalytic complexes at cell-matrix adhesions requires intact tyrosine residues Y31 and Y118 on paxillin and the localization of the focal adhesion kinase (FAK) at adhesion sites. In addition, we find that PTP1B specifically targets the Y925 on the focal adhesion target (FAT) domain of FAK at adhesion sites. Electrostatic analysis indicates that dephosphorylation of this residue promotes the closed conformation of the FAT 4-helix bundle, and its interaction with paxillin at adhesion sites.