Jun 11, 1999

Identification of an intramolecular interaction between the SH3 and guanylate kinase domains of PSD-95

The Journal of Biological Chemistry
A W McGee, D S Bredt


Postsynaptic density-95 (PSD-95/SAP-90) is a member of the membrane-associated guanylate kinase (MAGUK) family of proteins that assemble protein complexes at synapses and other cell junctions. MAGUKs comprise multiple protein-protein interaction motifs including PDZ, SH3 and guanylate kinase (GK) domains, and these binding sites mediate the scaffolding function of MAGUK proteins. Synaptic binding partners for the PDZ and GK domains of PSD-95 have been identified, but the role of the SH3 domain remains elusive. We now report that the SH3 domain of PSD-95 mediates a specific interaction with the GK domain. The GK domain lacks a poly-proline motif that typically binds to SH3 domains; instead, SH3/GK binding is a bi-domain interaction that requires both intact motifs. Although isolated SH3 and GK domains can bind in trans, experiments with intact PSD-95 molecules indicate that intramolecular SH3/GK binding dominates and prevents intermolecular associations. SH3/GK binding is conserved in the related Drosophila MAGUK protein DLG but is not detectable for Caenorhabditis elegans LIN-2. Many previously identified genetic mutations of MAGUKs in invertebrates occur in the SH3 or GK domains, and all of these mutations disrupt intramolecul...Continue Reading

  • References19
  • Citations86


Mentioned in this Paper

Saccharomyces cerevisiae Proteins
Transformation, Genetic
Precipitin Tests
SAP90-PSD95 Associated Proteins
Protein Self-association
Caenorhabditis elegans
Presynaptic density protein 95
Lin-23 protein, C elegans

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