Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have shown previously that Ca2+-channel agonists, which open Ca2+ channels, inhibit parathyroid hormone (PTH) secretion from dispersed bovine parathyroid cells, whereas Ca2+-channel antagonists, which close Ca2+ channels, stimulate PTH release. We now have tested the effects of mouse antibodies specific for purified alpha subunits of rat skeletal muscle Ca2+-channel proteins on PTH secretion by bovine parathyroid cells in vitro. Mouse antisera (MC-2, MC-3, MC-4) blocked the secretion of PTH from parathyroid cells incubated with 0.5 mM Ca2+ ions. Affinity-purified MC-4 antibodies inhibited PTH release in a concentration-dependent manner. Incubation of parathyroid cells with pertussis toxin markedly reduced MC-4-dependent inhibition of PTH secretion. Parathyroid cell membrane proteins were fractionated by NaDodSO4/polyacrylamide gel electrophoresis under either reducing or nonreducing conditions and immunoblotted with MC-4 antiserum. Antibodies bound to one major band of protein with Mr approximately equal to 150,000. These results suggest that the antibodies bind to Ca2+-channel alpha subunits and act as agonists that open the channels and inhibit PTH release.
 ...
PMID:Antibodies to an alpha subunit of skeletal muscle calcium channels regulate parathyroid cell secretion. 245 Dec 41

Mouse melanocortin receptors, MC1-R, MC3-R, MC4-R, and MC5-R, when expressed in HEK293 cells and stimulated with either alpha-melanocyte-stimulating hormone (alpha-MSH) or desacetyl-alpha-MSH, mediate increases in intracellular free calcium concentration ([Ca(2+)](i)) with EC(50) values between 0.3 and 4.3 nM. The increase in [Ca(2+)](i) is cholera toxin sensitive and pertussis toxin insensitive. The mechanism involves calcium mobilization from intracellular stores without a transient rise in inositol trisphosphate. Mouse agouti protein (55 nM) is a competitive antagonist of alpha-MSH (6-fold) and desacetyl-alpha-MSH (8-fold), coupling the mMC1-R to increased [Ca(2+)](i). Agouti protein (55 nM) significantly increased the EC(50) for alpha-MSH (3-fold), and 550 nM agouti protein significantly increased the EC(50) for desacetyl-alpha-MSH (4-fold), coupling the mMC4-R to a rise in [Ca(2+)](i). However, agouti protein antagonism of the MC4-R may not be competitive since there was a trend for the maximum response to also increase. There was no significant antagonism of the MC3-R and MC5-R by agouti protein (55 nM). Understanding the physiological relevance of the transduction of a calcium signal by melanocortin peptides may be important for future development of therapeutic targeting of the melanocortin receptors.
 ...
PMID:Melanocortin receptor-mediated mobilization of intracellular free calcium in HEK293 cells. 1116 Oct 2