<p>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 [<cite idref="PUB00018113"/>, <cite idref="PUB00001532"/>].Many IQ motifs are protein kinase C (PKC) phosphorylation sites [<cite idref="PUB00018114"/>, <cite idref="PUB00018115"/>].</p><p>Resolution of the 3D structure of scallop myosin has shown that the IQ motif forms a basic amphipathic helix [<cite idref="PUB00004175"/>].</p><p>Some proteins known to contain an IQ motif are listed below:<ul><li>A number of conventional and unconventional myosins.</li><li>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.</li><li>Neurogranin (NG/p17). Acts as a "third messenger" substrate of protein kinase C-mediated molecular cascades during synaptic development and remodeling.</li><li>Sperm surface protein Sp17.</li><li>Ras GTPase-activating-like protein IQGAP1. IQGAP1 contains 4 IQ motifs.</li></ul></p><p>This entry covers the entire IQ motif.</p>