Calcium signaling

Calcium signaling

Calcium can act in signal transduction after influx resulting from activation of ion channels or as a second messenger caused by indirect signal transduction pathways such as G protein-coupled receptors. Calcium is a common signaling mechanism, as once it enters the cytoplasm it exerts allosteric regulatory affects on many enzymes and proteins.

Calcium signaling through ion channels

Movement of calcium ions from the extracellular compartment to the intracellular compartment alters membrane depolarisation. This is seen in the heart, during the plateau phase of ventricular contraction. In this example, calcium acts to maintain depolarisation of the heart.

Calcium as a secondary messenger

Important physiological roles for calcium signaling include muscle contraction, and cellular motility, including the movement of flagella and cilia. Other biochemical roles of calcium include regulating enzyme activity, ion pumps, and components of the cytoskeleton. [Koolman, Roehm. "Color Atlas of Biochemistry". Thieme, 2005 ISBN 1-58890-247-1]

Signaling occurs when the cell is stimulated to release calcium ions (Ca2+) from intracellular stores. The resting concentration of Ca2+ in the cytoplasm is normally maintained in the range of 10 - 100 nM. To maintain this low concentration, Ca2+ is actively pumped from the cytosol and accumulated in the endoplasmic reticulum (ER), and sometimes in the mitochondria. Certain proteins of the cytoplasm and organelles act as buffers by binding Ca2+.

Specific signals can trigger a sudden increase in the cytoplasmic Ca2+ level up to 500 - 1 000 nM by opening channels in the endoplasmic reticulum or the plasma membrane. Many of Ca2+-mediated events occur when the released Ca2+ binds to and activates the regulatory protein calmodulin.

After cytoplasmic calcium has been depleted, Ca2+ can be imported from outside the cell by activation of "Store Operated Channels" (SOCs). This inflowing calcium current that results after stored calcium reserves have been released is referred to as Ca2+-release-activated Ca2+ current (ICRAC). The mechanisms through which ICRAC occurs are currently still under investigation, although two candidate molecules, Orai1 and STIM1 have been linked by several studies, and a model of store-operated calcium influx, involving these molecules, has been proposed. Recent studies have cited the phospholipase A2 beta, [Csutora P, Zarayskiy V, Peter K, Monje F, Smani T, Zakharov S, Litvinov D, Bolotina VM (2006) "J Biol Chem" 281 :34926-34945.] nicotinic acid adenine dinucleotide phosphate (NAADP), [Moccia F, Lim D, Nusco GA, Ercolano E, Santella L (2003) "FASEB" J 17: 1907-1909] and the protein STIM 1 [Baba Y, et al. (2006) "Proc Natl Acad Sci USA" 103:16704-9] as possible mediators of ICRAC.


*cite journal
quotes = yes
first=Ole H
title=Ca2+ signalling and Ca2+-activated ion channels in exocrine acinar cells
journal=Cell Calcium
publisher = | location = | issn =
pmid = 16107275
doi = 10.1016/j.ceca.2005.06.024
bibcode = | oclc =| id = | url = | language = | format = | accessdate = | laysummary = | laysource = | laydate = | quote =


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Calcium arsenate — Other names Calcium orthoarsenate Cucumber dust …   Wikipedia

  • Calcium-binding protein — Calcium binding proteins are proteins that participate in calcium cell signalling pathways by binding to Ca2+. The most ubiquitous Ca2+ sensing protein, found in all eukaryotic organisms including yeasts, is calmodulin. Intracellular storage and… …   Wikipedia

  • Intracellular calcium-sensing proteins — are proteins that act in the second messenger system. Examples include: calmodulin calnexin calreticulin gelsolin External links MeSH Intracellular+Calcium Sensing+Proteins …   Wikipedia

  • Neuronal calcium sensor — is a large family of proteins which work as calcium dependent molecular switches and includes members like Frequenin (NCS1), recoverin, GCAP, neurocalcin, visinin etc [1]. All the members carry 4 EF hand motifs (out of which only 2 or 3 bind… …   Wikipedia

  • Lipid signaling — Lipid signaling, broadly defined, refers to any biological signaling event involving a lipid messenger that binds and activates a receptor. Lipid signaling is thought to be qualitatively different from other classical signaling paradigms (such as …   Wikipedia

  • N-type calcium channel — Calcium channel, voltage dependent, N type, alpha 1B subunit Identifiers Symbols CACNA1B; BIII; CACNL1A5; CACNN; Cav2.2 External IDs …   Wikipedia

  • Neuronal calcium sensor-1 — PDB rendering based on 1g8i …   Wikipedia

  • Notch signaling pathway — Structure of the ligand binding region of the human NOTCH 1 receptor …   Wikipedia

  • Voltage-dependent calcium channel — Voltage dependent calcium channels (VDCC) are a group of voltage gated ion channels found in excitable cells (e.g., muscle, glial cells, neurons, etc.) with a permeability to the ion Ca2+.[1][2] These channels are slightly permeable to sodium… …   Wikipedia

  • CAMLG — Calcium modulating ligand, also known as CAMLG, is a human gene.cite web | title = Entrez Gene: CAMLG calcium modulating ligand| url = Cmd=ShowDetailView TermToSearch=819| accessdate = ] PBB… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”