Assemblage van signaalcomplexen

Signaling complexes are protein clusters assembled on a receptor's intracellular docking sites. This assembly aids signal transduction by grouping molecules into a single location.

Signaling complexes can be assembled in different ways. For example, some signals induce phosphorylation of either a receptor or phosphoinositides in the plasma membrane, creating a temporary docking site for signaling complex assembly.

In other cases, a large scaffold protein may help pre-assemble the signaling proteins on an inactive receptor. Scaffolds hold signaling proteins in close proximity, ensuring a rapid and selective response to the extracellular signal.

The specificity of protein-protein and protein-phospholipid interactions in the signaling complexes is controlled by multiple interaction domains in the signaling proteins.

The Src homology 2 or SH2 and phosphotyrosine-binding or PTB domains in the docking proteins bind to the phosphorylated tyrosines. In contrast, the Src homology 3 or SH3 domain binds to the proline-rich sequences.

The pleckstrin homology or PH domain recognizes the charged head groups of phosphoinositides allowing proteins to dock on the plasma membrane.