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Receptor‐mediated modulation of recombinant neuronal class E calcium channels
Author(s) -
Mehrke G,
Pereverzev A,
Grabsch H,
Hescheler J,
Schneider T
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00437-7
Subject(s) - pertussis toxin , somatostatin , transfection , hek 293 cells , g protein , microbiology and biotechnology , somatostatin receptor 2 , chemistry , calcium channel , voltage dependent calcium channel , biology , biophysics , somatostatin receptor , receptor , cell culture , calcium , biochemistry , endocrinology , organic chemistry , genetics
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 α 1Ed 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 α 1Ed ‐subunit. The application of the peptide hormone somatostatin, carbachol, ATP or adenosine reduced the amplitude of Ca 2+ and Ba 2+ 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‐ β ‐S or with the permanently activating agent GTP‐ γ ‐S also attenuated the somatostatin effect. The inhibition indicates that modulation of the α 1Ed ‐mediated Ca 2+ current involves pertussis toxin‐sensitive G‐proteins. The block of Ca 2+ and Ba 2+ inward currents by somatostatin is also found in cells expressing a truncated α 1Ed ‐subunit which lacks a 129‐bp fragment in the C‐terminus. This fragment corresponds to the major structural difference between two native human α 1E splice variants. As somatostatin inhibits inward currents through both, the cloned α 1Ed ‐ and the truncated α 1Ed‐DEL ‐subunit, the hormone‐mediated modulation is independent from the presence of the 129‐bp insertion in the C‐terminus.