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Differential modulation of N‐type α 1B and P/Q‐type α 1A calcium channels by different G protein β subunit isoforms
Author(s) -
Arnot Michelle I.,
Stotz Stephanie C.,
Jarvis Scott E.,
Zamponi Gerald W.
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.00203.x
Subject(s) - chemistry , n type calcium channel , biophysics , protein subunit , voltage dependent calcium channel , calcium channel , prepulse inhibition , gene isoform , r type calcium channel , calcium , t type calcium channel , biochemistry , biology , schizophrenia (object oriented programming) , organic chemistry , gene , computer science , programming language
1 Using transient calcium phosphate transfection into the human embryonic kidney tsa‐201 cell line and subsequent whole‐cell patch‐clamp protocols, we examined the tonic modulation of cloned N‐ and P/Q‐type calcium channels by five different G protein β subunits via strong depolarizing voltage prepulses. 2 For N‐ and P/Q‐type channels, the magnitude of inhibition was dependent on the G β subtype co‐expressed. 3 Both the absolute and relative magnitudes of G β subunit‐induced inhibition of P/Q‐type channels differed from those observed with the N‐type channel. 4 For each calcium channel subtype, kinetics of both the prepulse‐mediated recovery from inhibition and the re‐inhibition following the prepulse were examined for each of the G β subunits by varying either the duration between the pre‐ and the test pulse or the length of the prepulse. 5 For each channel subtype, we observed a differential G β subunit rank order with regard to the rates of re‐inhibition and recovery from inhibition. 6 On average, P/Q‐type channels exhibited more rapid rates of recovery from inhibition than those observed with N‐type channels. 7 Different G β subtypes mediated different degrees of slowing of activation kinetics. 8 The differential modulation of P/Q‐ and N‐type channels by various G β subtypes may provide a mechanism for fine tuning the amount of calcium entering the presynaptic nerve termini.