adaptor protein role SH2/SH3 adaptor protein role A role played by the entity interacting selectively and non-covalently and simultaneously with one or more signal transduction molecules, usually acting as a scaffold to bring these molecules into close proximity either using their own SH2/SH3 domains (e.g. Grb2) or those of their target molecules (e.g. SAM68). IMR:0000334 (obsolete) This term refers to the adaptor proteins that possesses both SH2 and SH3 domains, such as Grb2, Nck and Crk, and does not include adaptor proteins that contain only SH2 or PTB domains, such as the Shc family and the IRS family. related molecular function GO:0005070