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Protein protein interaction in G-protein coupled receptors: Homer proteins 

see review by Kreienkamp 2002

- described in detail for mGluR1 and mGluR5 (both signal by activation of PLC and mobilization of intracellular calcium via inositol trisphosphate receptors (I3PR)

- motif ("homer ligand"):

    P-P-X-X-F, binds to Ena/VASSP homology (EVA) domain of homer proteins (homer proteins are also called VESL, VASP/Ena-related gene upregulated during seizure and long-term potentiation)

- homer contains often an addition coiled-coil motif, by which they dimerize and have two binding sties for homer ligands

- homer proteins expressed in neurons, muscle and heart, together with their I3PR target molecule, but which GPCR involved besides mGluR in neurons is not yet studied

- functional significance:

    when homer dimerization motif mutated, no interaction with mGluR, kinetics of signal transduction are slowed down