IQ

Short calmodulin-binding motif containing conserved Ile and Gln residues.
IQ
SMART accession number:SM00015
Description: Calmodulin-binding motif.
Interpro abstract (IPR000048):

The IQ motif is an extremely basic unit of about 23 amino acids, whose conserved core usually fits the consensus A-x(3)-I-Q-x(2)-F-R-x(4)-K-K. The IQ motif, which can be present in one or more copies, serves as a binding site for different EF-hand proteins including the essential and regulatory myosin light chains, calmodulin (CaM), and CaM-like proteins [(PUBMED:1558751), (PUBMED:9141499)].Many IQ motifs are protein kinase C (PKC) phosphorylation sites [(PUBMED:1824695), (PUBMED:8424932)].

Resolution of the 3D structure of scallop myosin has shown that the IQ motif forms a basic amphipathic helix [(PUBMED:8127365)].

Some proteins known to contain an IQ motif are listed below:

  • A number of conventional and unconventional myosins.
  • Neuromodulin (GAP-43). This protein is associated with nerve growth. It is a major component of the motile "growth cones" that form the tips of elongating axons.
  • Neurogranin (NG/p17). Acts as a "third messenger" substrate of protein kinase C-mediated molecular cascades during synaptic development and remodeling.
  • Sperm surface protein Sp17.
  • Ras GTPase-activating-like protein IQGAP1. IQGAP1 contains 4 IQ motifs.

This entry covers the entire IQ motif.

GO function:protein binding (GO:0005515)
Family alignment:
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There are 16022 IQ domains in 5497 proteins in SMART's nrdb database.

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