Calmodulin has the Potential to Function as a Ca-Dependent Adaptor Protein.
Calmodulin (CaM) is a versatile Ca(2+)-binding protein that regulates the activity of numerous effector proteins in response to Ca(2+) signals. Several CaM-dependent regulatory mechanisms have been identified, including autoinhibitory domain displacement, sequestration of a ligand-binding site, active site reorganization, and target protein dimerization. We recently showed that the N- and C-lobes of animal and plant CaM isoforms could independently and sequentially bind to target peptides derived from the CaM-binding domain of Nicotiana tabacum mitogen-activated protein kinase phosphatase (NtMKP1), to form a 2:1 peptide:CaM complex. This suggests that CaM might facilitate the dimerization of NtMKP1, although the dimerization mechanism is distinct from the previously described simultaneous binding of other target peptides to CaM. The independent and sequential binding of the NtMKP1 peptides to CaM also suggests an alternative plausible scenario in which the C-lobe of CaM remains tethered to NtMKP1, and the N-lobe is free to recruit a second target protein to the complex, such as an NtMKP1 target. Thus, we hypothesize that CaM may be capable of functioning as a Ca(2+)-dependent adaptor or recruiter protein.
Yamniuk
Aaron P
AP
Structural Biology Research Group; Department of Biological Sciences; University of Calgary; Calgary Canada.
Rainaldi
Mario
M
Vogel
Hans J
HJ
J Biol Chem. 2004 Jan 9;279(2):928-36
14573600
Plant Cell Physiol. 2007 Feb;48(2):332-44
17218330
J Mol Biol. 2006 May 5;358(3):870-81
16530223
J Biol Chem. 1997 Apr 4;272(14):9252-9
9083059
FEBS Lett. 2002 Feb 20;513(1):107-13
11911888
Plant Mol Biol. 2000 Mar;42(4):591-601
10809005
Biochemistry. 1999 Sep 21;38(38):12320-32
10493800
Structure. 2005 Dec;13(12):1881-6
16338416
Mol Biotechnol. 2004 May;27(1):33-57
15122046
Biochemistry. 1991 Jun 25;30(25):6247-51
1647818
Physiol Rev. 1999 Jul;79(3):661-82
10390515
Annu Rev Plant Biol. 2005;56:435-66
15862103
J Biol Chem. 2007 Mar 2;282(9):6031-42
17202149
Structure. 2006 Oct;14(10):1547-56
17027503
Biochemistry. 1998 Jan 6;37(1):227-36
9425043
J Biol Chem. 1998 Nov 13;273(46):30328-35
9804795
Nat Struct Mol Biol. 2005 Dec;12(12):1108-15
16299511
J Mol Biol. 2003 Apr 18;328(1):193-204
12684008
Biochem J. 1996 May 1;315 ( Pt 3):1021-6
8645139
J Biol Chem. 2004 May 28;279(22):23504-9
14988396
Nature. 2002 Jan 24;415(6870):396-402
11807546
Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19326-31
17151196
J Biol Chem. 2006 Feb 3;281(5):2876-81
16317001
EMBO Rep. 2006 May;7(5):506-11
16582881
Nature. 2001 Apr 26;410(6832):1120-4
11323678
J Biol Chem. 2002 Feb 22;277(8):6550-8
11748245
Biopolymers. 2001 Jan;58(1):50-62
11072229
Calcium Bind Proteins. 2006 Oct-Dec;1(4):203-212
28757812
J Biol Chem. 2000 Nov 17;275(46):36334-40
10926933
J Biol Chem. 2005 Nov 25;280(47):39569-81
16183637