Function of the SH2 Domain

Phosphotyrosine-SH2 interactions are involved in passing on the signal for at least three different types of transmembrane receptor  

The T cell receptors (see Chapter 11) are an example of receptors composed of several subimits. Ligand binding to the receptor activates an associated tyrosine kinase which phosphorylates Tyr residues in the cytoplasmic region of the receptor and thus creates binding sites for SH2 domains of effector molecules downstream. 

The receptors for cytokines and interferons are the starting point for signal transduction chains that bring about an activation of transcription factors. The signaling pathway involves the Janus protein kinase and Stat transcription factors (see 11.1.4). Phosphoty-rosine-SH2 interactions are also involved in several steps of signal transduction here. 

The SH2 domains also have diverse linking functions in signal reactions sequential to activated receptors. The adaptor proteins should be mentioned in particular here (see 8.5) their SH2 groups are used to interlink signal proteins. 

Coupling of signal proteins by phosphotyrosine-SH2 interactions can serve different purposes  

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