An adaptor protein is a protein which is accessory to main proteins in a signal transduction pathway. These proteins tend to lack any intrinsic enzymatic activity themselves but instead mediate specific protein-protein interactions that drive the formation of protein complexes. Examples of adaptor proteins include MyD88, Grb2 and Shc.
[edit] Signalling components
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.
[edit] Domains
Adaptor proteins usually contain several domains within their structure (e.g., Src homology 2 (SH2) and SH3 domains) which allow specific interactions with several other specific proteins. SH2 domains recognise specific amino acid sequences within proteins containing phosphotyrosine residues and SH3 domains recognise proline-rich sequences within specific peptide sequence contexts of proteins.
There are many other types of interaction domains found within adaptor and other signalling proteins which allow a rich diversity of specific and coordinated protein-protein interactions to occur within the cell during signal transduction.
Genes encoding adaptor proteins include:
- GRAP - GRB2-related adaptor protein
- GRAP2 - GRB2-related adaptor protein 2
- LDLRAP1 - low density lipoprotein receptor adaptor protein 1
- NCK1 - NCK adaptor protein 1
- NCK2 - NCK adaptor protein 2
- NOS1AP - nitric oxide synthase 1 (neuronal) adaptor protein
- PIK3AP1 - phosphoinositide-3-kinase adaptor protein 1
- SH2B1 - SH2B adaptor protein 1
- SH2B2 - SH2B adaptor protein 2
- SH2B3 - SH2B adaptor protein 3
- SHB - Src homology 2 domain containing adaptor protein B
- SLC4A1AP - solute carrier family 4 (anion exchanger), member 1, adaptor protein
- GAB2, GRB2-associated binding protein 2
[edit] See also
