The Sp domain has previously been suggested to bind to glycosaminoglycans, as it promotes aggrecan hydrolysis [ 10] and binding to the extracellular matrix [ 10].
Cell binding to the extracellular matrix (ECM) is essential for cell and tissue functions.
Therefore, AChBPs still represent the best template for the characterization of ligand binding to the extracellular ligand-binding domain of nAChRs (Cecchini and Changeux, 2015).
The Wnt modulation by Wise is mediated by its binding to the extracellular domain of Lrp6.
Finally, although the significance is unclear, DOCK180 is phosphorylated upon Integrin binding to the extracellular matrix [65].
Ligand binding to the extracellular domain of transmembrane RTKs triggers receptor dimerization and autophosphorylation of an intracellular kinase domain.
VEGF binding to the extracellular domain of the VEGFR results in dimerization and autophosphorylation of the intracellular tyrosine kinases [8].
Ligand binding to the extracellular domain of EGFR induces receptor dimerization, activation of its kinase domain, and phosphorylation of tyrosine residues in its carboxy terminal tail [1].
SPARC is a matricellular protein that modulates cell adhesion and growth and modulates cell-matrix interactions by binding to the extracellular matrix [17].
Additional studies have also implicated direct binding to the extracellular matrix (ECM) and transfer to the cell membrane via laminin-5 [7], a process which may also involve activation of and transfer along cell surface filopodia [8], [9].
In mammalian cells it is known that integrin binding to the extracellular matrix induces the activation of Rac GTPases, and we have previously shown that Rac1 and Rac2 are necessary for a proper encapsulation response in Drosophila larvae.
