Calmodulin: Difference between revisions
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[[Calcium|Calcium binding]] protein involved in [[Calcium signalling|intracellular calcium signalling.]] <ref>Alberts et al. Molecular Biology of the Cell (5th Ed)</ref> | [[Calcium|Calcium binding]] protein involved in [[Calcium signalling|intracellular calcium signalling.]] <ref>Alberts et al. Molecular Biology of the Cell (5th Ed)</ref> | ||
=== Structure === | |||
Highly conserved sequence of 152 [[Amino acids|amino acids]] <ref>http://www.ncbi.nlm.nih.gov/protein/CAA36839.1</ref>. | |||
There are four [[EFh domains|EFh domains]] which are responsible to bind 4 [[Calcium|Ca<sup>2+</sup>]] [[Ions|ions]].<ref>http://smart.embl-heidelberg.de/smart/job_status.pl?jobid=939661123169621289746763YwAuDuwGQT</ref> <br> | |||
The arrangement of the Ca<sup>2+</sup> binding sites are brought about by the N- and C- terminal lobes <ref>http://www.cell-signalling.org/csb/004/csb004.pdf</ref>. | |||
Calmodulin are dumbbell shaped protein where long and flexible [[Alpha helix|alpha helix]] connects two [[Globular domains|globular domains]]. Each domain is assembled from two [[EF-hand|EF-hand]] regions attached to antiparalel [[Beta-sheet|beta-sheet]]. Ca<sup>2+</sup> binds to [[Glutamate|glutamate]] and [[Aspartate|aspartate]] residues placed in the loop of EF-hand.<ref>John T.Hancock (2005).Cell signalling. New York:Oxford University press</ref><sup></sup> | |||
It is closely related to [[Troponin C|Troponin C]], which is found in the [[Actin filaments|Actin filaments]] of [[Skeletal muscle|Skeletal muscle]] cells.<ref>W.Boron and E Boulpaep, (2012) Medical Physiology (2nd Ed) p258</ref><br> | |||
=== Function === | === Function === | ||
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Two or more Ca<sup>2+</sup> ions bind to induce a [[Conformational change|conformational change]] and activate calmodulin <ref>Alberts et al. Molecular Biology of the Cell (5th Ed)</ref>. This results in amplifying the affinity of Ca<sup>2+</sup> molecule which later affects other signalling components such as [[CaMKs|Ca<sup>2+</sup>/calmodulin-dependent protein kinases]] (CaMKs), [[Myosin light chain kinase|myosin light chain kinase]] (MLCK), [[Phosphorylase kinase|phosphorylase kinase]], [[Neuromodulin|neuromodulin]] and so on <ref>http://www.cell-signalling.org/csb/004/csb004.pdf</ref>. | Two or more Ca<sup>2+</sup> ions bind to induce a [[Conformational change|conformational change]] and activate calmodulin <ref>Alberts et al. Molecular Biology of the Cell (5th Ed)</ref>. This results in amplifying the affinity of Ca<sup>2+</sup> molecule which later affects other signalling components such as [[CaMKs|Ca<sup>2+</sup>/calmodulin-dependent protein kinases]] (CaMKs), [[Myosin light chain kinase|myosin light chain kinase]] (MLCK), [[Phosphorylase kinase|phosphorylase kinase]], [[Neuromodulin|neuromodulin]] and so on <ref>http://www.cell-signalling.org/csb/004/csb004.pdf</ref>. | ||
In the case of MLCK, four Ca<sup>2+</sup> ions bind Calmodulin to form a Ca<sup>2+</sup>-CaM complex. It is this complex that then activates MLCK, leading to the [[Phosphorylation]] of the myosin light chain and increased [[ATPase]] activity in smooth muscle cells. <ref>W.Boron and E Boulpaep, (2012) Medical Physiology (2nd Ed) p258</ref> | In the case of MLCK, four Ca<sup>2+</sup> ions bind Calmodulin to form a Ca<sup>2+</sup>-CaM complex. It is this complex that then activates MLCK, leading to the [[Phosphorylation]] of the myosin light chain and increased [[ATPase]] activity in smooth muscle cells. <ref>W.Boron and E Boulpaep, (2012) Medical Physiology (2nd Ed) p258</ref> | ||
=== References === | === References === | ||
<references /> | <references /> | ||
Latest revision as of 01:47, 29 November 2013
Calcium binding protein involved in intracellular calcium signalling. [1]
Structure
Highly conserved sequence of 152 amino acids [2].
There are four EFh domains which are responsible to bind 4 Ca2+ ions.[3]
The arrangement of the Ca2+ binding sites are brought about by the N- and C- terminal lobes [4].
Calmodulin are dumbbell shaped protein where long and flexible alpha helix connects two globular domains. Each domain is assembled from two EF-hand regions attached to antiparalel beta-sheet. Ca2+ binds to glutamate and aspartate residues placed in the loop of EF-hand.[5]
It is closely related to Troponin C, which is found in the Actin filaments of Skeletal muscle cells.[6]
Function
Calmodulin functions as a multi-purpose intracellular receptor, governing many Ca2+ regulated processes. [7]
Two or more Ca2+ ions bind to induce a conformational change and activate calmodulin [8]. This results in amplifying the affinity of Ca2+ molecule which later affects other signalling components such as Ca2+/calmodulin-dependent protein kinases (CaMKs), myosin light chain kinase (MLCK), phosphorylase kinase, neuromodulin and so on [9].
In the case of MLCK, four Ca2+ ions bind Calmodulin to form a Ca2+-CaM complex. It is this complex that then activates MLCK, leading to the Phosphorylation of the myosin light chain and increased ATPase activity in smooth muscle cells. [10]
References
- ↑ Alberts et al. Molecular Biology of the Cell (5th Ed)
- ↑ http://www.ncbi.nlm.nih.gov/protein/CAA36839.1
- ↑ http://smart.embl-heidelberg.de/smart/job_status.pl?jobid=939661123169621289746763YwAuDuwGQT
- ↑ http://www.cell-signalling.org/csb/004/csb004.pdf
- ↑ John T.Hancock (2005).Cell signalling. New York:Oxford University press
- ↑ W.Boron and E Boulpaep, (2012) Medical Physiology (2nd Ed) p258
- ↑ Alberts et al. Molecular Biology of the Cell (5th Ed).
- ↑ Alberts et al. Molecular Biology of the Cell (5th Ed)
- ↑ http://www.cell-signalling.org/csb/004/csb004.pdf
- ↑ W.Boron and E Boulpaep, (2012) Medical Physiology (2nd Ed) p258