Summary: IQ calmodulin-binding motif
This is the Wikipedia entry entitled "IQ calmodulin-binding motif". More...
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IQ calmodulin-binding motif Edit Wikipedia article
|Structure of the regulatory domain of scallop myosin at 2 A resolution.|
Calmodulin (CaM) is recognized as a major calcium (Ca2+) sensor and orchestrator of regulatory events through its interaction with a diverse group of cellular proteins. Three classes of recognition motifs exist for many of the known CaM binding proteins; the IQ motif as a consensus for Ca2+-independent binding and two related motifs for Ca2+-dependent binding, termed 1-14 and 1-5-10 based on the position of conserved hydrophobic residues.
The regulatory domain of scallop myosin is a three-chain protein complex that switches on this motor in response to Ca2+ binding. Side-chain interactions link the two light chains in tandem to adjacent segments of the heavy chain bearing the IQ-sequence motif. The Ca2+-binding site is a novel EF hand motif on the essential light chain and is stabilized by linkages involving the heavy chain and both light chains, accounting for the requirement of all three chains for Ca2+binding and regulation in the intact myosin molecule.
- ^ Houdusse A, Cohen C (January 1996). "Structure of the regulatory domain of scallop myosin at 2 A resolution: implications for regulation". Structure 4 (1): 21–32. doi:10.1016/S0969-2126(96)00006-8. PMID 8805510.
- ^ Rhoads AR, Friedberg F (April 1997). "Sequence motifs for calmodulin recognition". FASEB J. 11 (5): 331–40. PMID 9141499.
- ^ Xie X, Harrison DH, Schlichting I, Sweet RM, Kalabokis VN, Szent-Györgyi AG, Cohen C (March 1994). "Structure of the regulatory domain of scallop myosin at 2.8 A resolution". Nature 368 (6469): 306–12. doi:10.1038/368306a0. PMID 8127365.
IQ calmodulin-binding motif Provide feedback
Xie X, Harrison DH, Schlichting I, Sweet RM, Kalabokis VN, Szent-Gyorgyi AG, Cohen C; , Nature 1994;368:306-312.: Structure of the regulatory domain of scallop myosin at 2.8 A resolution. PUBMED:8127365 EPMC:8127365
External database links
This tab holds annotation information from the InterPro database.
InterPro entry 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.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||protein binding (GO:0005515)|
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- the UniProt description of the protein sequence
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We make a range of alignments for each Pfam-A family:
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Curation and family details
|Author:||Ponting C, Schultz J, Bork P|
|Number in seed:||345|
|Number in full:||16654|
|Average length of the domain:||20.70 aa|
|Average identity of full alignment:||32 %|
|Average coverage of the sequence by the domain:||5.40 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||22|
|Download:||download the raw HMM for this family|
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There are 4 interactions for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the IQ domain has been found. There are 44 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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