IQ calmodulin-binding motif

Available protein structures:
Pfam	structures/ECOD
PDB	RCSB PDB;PDBe;PDBj
PDBsum	structure summary
PDB	1b7t,1br1,1br2,1br4,1d0x,1d0y,1d0z,1d1a,1d1b,1d1c,1dfk,1dfl,1fmv,1fmw,1jwy,1jx2,1kk7,1kk8,1kqm,1kwo,1l2o,1lkx,1lvk,1mma,1mmd,1mmg,1mmn,1mnd,1mne,1oe9,1qvi,1s5g,1scm,1sr6,1vom,1w7i,1w7j,1wdc,2mys

IQ calmodulin-binding motif
IQ calmodulin-binding motif
	Structure of the regulatory domain of scallop myosin at 2 A resolution.
Identifiers
Symbol	IQ
Pfam	PF00612
InterPro	IPR000048
SMART	SM00015
PROSITE	PS50096
SCOP2	1wdc/SCOPe/SUPFAM
Pfam
Available protein structures:
Pfam	structures/ECOD
PDB	RCSB PDB;PDBe;PDBj
PDBsum	structure summary
PDB	1b7t,1br1,1br2,1br4,1d0x,1d0y,1d0z,1d1a,1d1b,1d1c,1dfk,1dfl,1fmv,1fmw,1jwy,1jx2,1kk7,1kk8,1kqm,1kwo,1l2o,1lkx,1lvk,1mma,1mmd,1mmg,1mmn,1mnd,1mne,1oe9,1qvi,1s5g,1scm,1sr6,1vom,1w7i,1w7j,1wdc,2mys

TheIQ calmodulin-binding motifis anamino acid sequence motifcontaining the following sequence:

[FILV]Qxxx[RK]Gxxx[RK]xx[FILVWY]

The term "IQ" refers to the first two amino acids of the motif:isoleucine(commonly) andglutamine(invariably).

Function

Calmodulin(CaM) is recognized as a majorcalcium(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 conservedhydrophobicresidues.^[2]

Example

The regulatory domain of scallopmyosinis 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 novelEF handmotif 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.^[3]

References

^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.doi:10.1096/fasebj.11.5.9141499.PMID 9141499.S2CID 1877645.
^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.Bibcode:1994Natur.368..306X.doi:10.1038/368306a0.PMID 8127365.S2CID 4279198.

This article incorporates text from the public domainPfamandInterPro:IPR000048

[pmid8805510-1] 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.

[pmid9141499-2] Rhoads AR, Friedberg F (April 1997)."Sequence motifs for calmodulin recognition".FASEB J.11(5): 331–40.doi:10.1096/fasebj.11.5.9141499.PMID 9141499.S2CID 1877645.

[pmid8127365-3] 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.Bibcode:1994Natur.368..306X.doi:10.1038/368306a0.PMID 8127365.S2CID 4279198.

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