Cloned and expressed rat Ca2+-sensing receptor.
We have stably expressed cDNA for the rat brain Ca2+ sensing receptor in Chinese hamster ovary cells. Stimulation of phosphatidylinositol hydrolysis and arachidonic acid (AA) release displayed markedly cooperative responses to Ca2+ with Hill coefficients of 4-5. Both phosphatidylinositol and AA responses were not detected below a threshold of 1.5 mM Ca2+. Mg2+ behaved as a partial agonist with only half the maximal inositol phosphate and AA responses displayed by Ca2+ and with a more shallow concentration-response slope. The potency of Mg2+ in augmenting inositol phosphate and AA responses, in the presence of 1.5 mM Ca2+, implies that serum Mg2+ concentrations attained in clinical conditions will influence the Ca2+-sensing receptor.
Ruat
M
M
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Snowman
A M
AM
Hester
L D
LD
Snyder
S H
SH
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D008274:Magnesium / Q000097:blood / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism; D051381:Rats; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D015290:Second Messenger Systems; D014162:Transfection
D018076:DNA, Complementary; D010716:Phosphatidylinositols; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface; C473605:extracellular calcium cation-sensing receptor, rat; D016718:Arachidonic Acid; D008274:Magnesium; D002118:Calcium