Calmodulin


Calmodulin

[
http://www.pdb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb44_1.html more details...] ] Calmodulin (CaM) (an abbreviation for CALcium MODULated proteIN) is a calcium-binding protein expressed in all eukaryotic cells. It can bind to and regulate a number of different protein targets, thereby affecting many different cellular functions.cite journal | author = Stevens FC | title = Calmodulin: an introduction | journal = Can. J. Biochem. Cell Biol. | volume = 61 | issue = 8 | pages = 906–10 | year = 1983 | pmid = 6313166 | doi = | issn = ] cite journal | author = Chin D, Means AR | title = Calmodulin: a prototypical calcium sensor | journal = Trends Cell Biol. | volume = 10 | issue = 8 | pages = 322–8 | year = 2000 | pmid = 10884684 | doi = 10.1016/S0962-8924(00)01800-6 ]

Function

CaM mediates processes such as inflammation, metabolism, apoptosis, muscle contraction, intracellular movement, short-term and long-term memory, nerve growth and the immune response. CaM is expressed in many cell types and can have different subcellular locations, including the cytoplasm, within organelles, or associated with the plasma or organelle membranes. Many of the proteins that CaM binds are unable to bind calcium themselves, and as such use CaM as a calcium sensor and signal transducer. CaM can also make use of the calcium stores in the endoplasmic reticulum, and the sarcoplasmic reticulum. CaM undergoes a conformational change upon binding to calcium, which enables it to bind to specific proteins for a specific response. CaM can bind up to four calcium ions, and can undergo post-translational modifications, such as phosphorylation, acetylation, methylation and proteolytic cleavage, each of which can potentially modulate its actions. Calmodulin can also bind to edema factor toxin from the anthrax bacteria.

tructure

Calmodulin is a small, acidic protein approximately 148 amino acids long (16706 Dalton) and, as such, is a favorite for testing protein simulation software. It contains four EF-hand "motifs", each of which binds a Ca2+ ion. The protein has two approximately symmetrical domains, separated by a flexible "hinge" region. Calcium participates in an intracellular signalling system by acting as a diffusible second messenger to the initial stimuli.

Mechanism

Calcium is bound via the use of the EF hand motif, which supplies an electronegative environment for ion coordination. After calcium binding, hydrophobic methyl groups from methionine residues become exposed on the protein via conformational change. This presents hydrophobic surfaces, which can in turn bind to Basic Amphiphilic Helices (BAA helices) on the target protein. These helices contain complementary hydrophobic regions. The flexibilily of Calmodulin's hinged region allows the molecule to "wrap around" its target. This property allows it to tightly bind to a wide range of different target proteins.

Family members

* Calmodulin 1 (Gene|CALM1)
* Calmodulin 2 (Gene|CALM2)
* Calmodulin 3 (Gene|CALM3)
* Calmodulin-like 1 (Gene|CALML1)
* Calmodulin-like 3 (Gene|CALML3)
* Calmodulin-like 4 (Gene|CALML4)
* Calmodulin-like 5 (Gene|CALML5)
* Calmodulin-like 6 (Gene|CALML6)

Other calcium-binding proteins

Calmodulin belongs to one of the two main groups of calcium-binding proteins, called EF hand proteins. The other group, called annexins, bind calcium and phospholipid (e.g., lipocortin). Many other proteins bind calcium, although binding calcium may not be considered their principal function in the cell.

ee also

*Protein kinase
*Ca2+/calmodulin-dependent protein kinase
*Douglas Stirling

References

External links

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Look at other dictionaries:

  • Calmodulin 1 — (phosphorylase kinase, delta) PDB rendering based on 1a29 …   Wikipedia

  • Calmodulin — Vorhandene Strukturdaten: s. UniProt Masse/Länge …   Deutsch Wikipedia

  • Calmodulin — Calmodulin, in allen Eukaryotenzellen vorhandenes, calciumbindendes Protein, das als Ca2+ Calmodulin Komplex verschiedene Enzyme aktiviert und so in das Stoffwechselgeschehen der Zelle eingreift …   Deutsch wörterbuch der biologie

  • calmodulin — calmodulin. См. кальмодулин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • calmodulin — [kal mä′jo͞o lin΄, kal mä′jəlin΄] n. [ CAL(CIUM) + MODUL(ATE) + IN1] a protein in nearly all cells that binds to calcium and regulates many important cell functions, as nerve impulse transmissions and muscle action …   English World dictionary

  • Calmodulin — Cal|mo|du|lin [Kurzw. aus ↑ Calcium u. Modulation; ↑ in (3)], das; s, e: ein Protein aus 148 Aminosäuren, das als intrazellulärer Rezeptor für Calcium Ionen zahlreiche Ca abhängige Stoffwechselprozesse im Organismus steuert. * * * Calmodulin  … …   Universal-Lexikon

  • calmodulin — A small, ubiquitous eukaryotic protein that binds calcium ions, thereby becoming the agent for many of the cellular effects long ascribed to calcium ions. This calcium protein complex binds to the apoenzyme, to form the holoenzyme, of certain… …   Medical dictionary

  • calmodulin — noun Etymology: calcium + modulate + 1 in Date: 1978 a calcium binding protein that mediates cellular metabolic processes (as the contraction of muscle fibers) by regulating the activity of calcium dependent enzymes …   New Collegiate Dictionary

  • calmodulin — Ubiquitous and highly conserved calcium binding protein (17 kD) with four EF hand binding sites for calcium (3 in yeast). Ancestor of troponin C, leiotonin C, and parvalbumin …   Dictionary of molecular biology

  • calmodulin — /kal moj euh lin/, n. Biochem. a calcium binding protein occurring in many tissues and participating in the regulation of many biochemical and physiological processes. [1975 80; CAL(CIUM) + MODUL(ATE) + IN2] * * * …   Universalium


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