Signal transducing adaptor protein

[1] Adaptor proteins contain a variety of protein-binding modules that link protein-binding partners together and facilitate the creation of larger signaling complexes.

These proteins tend to lack any intrinsic enzymatic activity themselves,[2] instead mediating specific protein–protein interactions that drive the formation of protein complexes.

Much of the specificity of signal transduction depends on the recruitment of several signalling components such as protein kinases and G-protein GTPases into short-lived active complexes in response to an activating signal such as a growth factor binding to its receptor.

Adaptor proteins usually contain several domains within their structure (e.g., Src homology 2 (SH2) and SH3 domains) that allow specific interactions with several other specific proteins.

There are many other types of interaction domains found within adaptor and other signalling proteins that allow a rich diversity of specific and coordinated protein–protein interactions to occur within the cell during signal transduction.