Receptor-mediated modulation of recombinant neuronal class E calcium channels.
The modulation of a cloned neuronal calcium channel was studied in a human embryonic kidney cell line (HEK293). The HEK293 cells were stably transfected with the alpha1Ed cDNA, containing the pore forming subunit of a neuronal class E calcium channel. Inward currents of 25 +/- 1.9 pA/pF (n = 79) were measured with the cloned alpha1Ed-subunit. The application of the peptide hormone somatostatin, carbachol, ATP or adenosine reduced the amplitude of Ca2+ and Ba2+ inward currents and exhibited a slowing of inactivation. This inhibitory effect by somatostatin was significantly impaired after pre-incubating the transfected cell line with pertussis toxin (PTX). Internal perfusion of the cells with the G-protein-inactivating agent GDP-beta-S or with the permanently activating agent GTP-gamma-S also attenuated the somatostatin effect. The inhibition indicates that modulation of the alpha1Ed-mediated Ca2+ current involves pertussis toxin-sensitive G-proteins. The block of Ca2+ and Ba2+ inward currents by somatostatin is also found in cells expressing a truncated alpha1Ed-subunit which lacks a 129-bp fragment in the C-terminus. This fragment corresponds to the major structural difference between two native human alpha1E splice variants. As somatostatin inhibits inward currents through both, the cloned alpha1Ed- and the truncated alpha1Ed-DEL-subunit, the hormone-mediated modulation is independent from the presence of the 129-bp insertion in the C-terminus.
Mehrke
G
G
Institute of Neurophysiology, University of Köln, Germany.
Pereverzev
A
A
Grabsch
H
H
Hescheler
J
J
Schneider
T
T
D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D001464:Barium / Q000378:metabolism; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000737:chemistry; D020746:Calcium Channels, L-Type; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D003001:Cloning, Molecular; D019204:GTP-Binding Proteins / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D007668:Kidney; D007700:Kinetics; D046911:Macromolecular Substances; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D037342:Pertussis Toxin; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013004:Somatostatin / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D001464:Barium; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D013004:Somatostatin; C023427:guanosine 5'-O-(2-thiodiphosphate); D000255:Adenosine Triphosphate; D002217:Carbachol; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000241:Adenosine; D002118:Calcium