{PDOC50096}
{PS50096; IQ}
{BEGIN}
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* IQ motif profile *
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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 (see <PDOC00018>) including the  essential and
regulatory myosin light chains, calmodulin (CaM), and CaM-like proteins [1,2].
Many IQ motis are protein kinase C (PKC) phosphorylation sites [3,4].

Resolution  of the 3D structure of scallop myosin has shown that the IQ motif
forms a basic amphipathic helix [5].

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

 - A number of conventional and unconventional myosins.
 - Neuromodulin  (GAP-43)  (see  <PDOC00344>). 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.

The profile we developed covers the entire IQ motif.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: 2.

-Last update: December 2001 / First entry.

[ 1] Cheney R.E., Mooseker M.S.
     "Unconventional myosins."
     Curr. Opin. Cell Biol. 4:27-35(1992).
     PubMed=1558751
[ 2] Rhoads A.R., Friedberg F.
     "Sequence motifs for calmodulin recognition."
     FASEB J. 11:331-340(1997).
     PubMed=9141499
[ 3] Baudier J., Deloulme J.C., Van Dorsselaer A., Black D., Matthes H.W.D.
     "Purification and characterization of a brain-specific protein kinase
     C substrate, neurogranin (p17). Identification of a consensus amino
     acid sequence between neurogranin and neuromodulin (GAP43) that
     corresponds to the protein kinase C phosphorylation site and the
     calmodulin-binding domain."
     J. Biol. Chem. 266:229-237(1991).
     PubMed=1824695
[ 4] Chen S.J., Klann E., Gower M.C., Powell C.M., Sessoms J.S., Sweatt J.D.
     "Studies with synthetic peptide substrates derived from the neuronal
     protein neurogranin reveal structural determinants of potency and
     selectivity for protein kinase C."
     Biochemistry 32:1032-1039(1993).
     PubMed=8424932
[ 5] Xie X., Harrison D.H., Schlichting I., Sweet R.M., Kalabokis V.N.,
     Szent-Gyorgyi A.G., Cohen C.
     "Structure of the regulatory domain of scallop myosin at 2.8 A
     resolution."
     Nature 368:306-312(1994).
     PubMed=8127365; DOI=10.1038/368306a0
{END}