Modulation of a brain voltage-gated K+ channel by syntaxin 1A requires the physical interaction of Gbetagamma with the channel.
Recently we suggested that direct interactions between voltage-gated K(+) channels and proteins of the exocytotic machinery, such as those observed between the Kv1.1/Kvbeta channel, syntaxin 1A, and SNAP-25 may be involved in neurotransmitter release. Furthermore, we demonstrated that the direct interaction with syntaxin 1A enhances the fast inactivation of Kv1.1/Kvbeta1.1 in oocytes. Here we show that G-protein betagamma subunits play a crucial role in the enhancement of inactivation by syntaxin 1A. The effect caused by overexpression of syntaxin 1A is eliminated in the presence of chelators of endogenous betagamma subunits in the whole cell and at the plasma membrane. Conversely, enhancement of inactivation caused by overexpression of beta(1)gamma(2) subunits is eliminated upon knock-down of endogenous syntaxin or its scavenging at the plasma membrane. We further show that the N terminus of Kv1.1 binds brain synaptosomal and recombinant syntaxin 1A and concomitantly binds beta(1)gamma(2); the binding of beta(1)gamma(2) enhances that of syntaxin 1A. Taken together, we suggest a mechanism whereby syntaxin and G protein betagamma subunits interact concomitantly with a Kv channel to regulate its inactivation.
Michaelevski
Izhak
I
Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, 69978 Ramat-Aviv, Israel.
Chikvashvili
Dodo
D
Tsuk
Sharon
S
Fili
Oded
O
Lohse
Martin J
MJ
Singer-Lahat
Dafna
D
Lotan
Ilana
I
D000818:Animals; D000954:Antigens, Surface / Q000502:physiology*; D001483:Base Sequence; D001921:Brain / Q000378:metabolism / Q000502:physiology*; D017931:DNA Primers; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015640:Ion Channel Gating; D009419:Nerve Tissue Proteins / Q000502:physiology*; D015221:Potassium Channels / Q000378:metabolism / Q000502:physiology*; D017729:Presynaptic Terminals / Q000502:physiology; D011485:Protein Binding; D050827:Syntaxin 1; D014982:Xenopus laevis
D000954:Antigens, Surface; D017931:DNA Primers; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D050827:Syntaxin 1; D019204:GTP-Binding Proteins