[Extracellular Ca2+ signaling: first messenger in animals and plants].
It is well known that calcium acts as a vital intracellular second messenger that governs a large array of cellular processes. However, the molecular identification of a receptor for extracellular Ca2+, the extracellular calcium-sensing receptor, has opened up the possibility that Ca2+might also function as a messenger outside the cell. In animals, the Ca2+ sensor is the well-characterized extracellular-Ca2+- sensing receptor (CaR), a G- protein -coupled receptor originally isolated from the parathyroid gland. In addition, other receptors, channels and membrane proteins are all sensitive to external Ca2+ fluctuations. Recently, Han et al have cloned a receptor protein for extracellular calcium in Arabidopsis, which plays a key role in Ca2+-induced stomatal closing. Thus, the cloning of these receptors has prompted the consideration of Ca2+ also functioning as a 'first messenger' in animals and plants.
Zhao
Xin
X
College of Life Science, Capital Normal University, Beijing, China. zhaox0521@sina.com
Pei
Zhen-Ming
ZM
He
Yi-Kun
YK
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology*; D005110:Extracellular Space / Q000378:metabolism*; D007477:Ions; D018521:Plant Physiological Phenomena; D010944:Plants / Q000378:metabolism*; D044169:Receptors, Calcium-Sensing / Q000378:metabolism*; D015290:Second Messenger Systems / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
D015220:Calcium Channels; D007477:Ions; D044169:Receptors, Calcium-Sensing; D002118:Calcium