Modifications in the biophysical properties of connexin43 channels by a peptide of the cytoplasmic loop region.
Connexin43 (Cx43) channels reside in at least 3 states: closed, open, or residual. It is hypothesized that the residual state results from the interaction of an intracellular "gating element" with structures at the vestibule of the pore. Recently, we showed in vitro that there is an intramolecular interaction of the carboxyl-terminal domain (referred to as "CT") with a region in the cytoplasmic loop of Cx43 (amino acids 119 to 144; referred to as "L2"). Here, we assessed whether the L2 region was able to interact with the gating particle in a functional channel. Cx43 channels were recorded in the presence of a peptide corresponding to the L2 region, delivered via the patch pipette. This manipulation did not modify unitary conductance, but decreased the frequency of transitions into the residual state, prolonged open time, and altered the voltage dependence of the channel in a manner analogous to that observed after truncation of the CT domain. The latter correlated with the ability of the peptide to bind to the CT domain, as determined by mirror resonance spectroscopy. Overall, we propose that the L2 acts as a "receptor" that interacts with a flexible intracellular gating element during channel gating. The full text of this article is available online at http://circres.ahajournals.org.
Seki
Akiko
A
Department of Pharmacology, State University of New York Upstate Medical University, Syracuse 13210, USA.
Duffy
Heather S
HS
Coombs
Wanda
W
Spray
David C
DC
Taffet
Steven M
SM
Delmar
Mario
M
D000818:Animals; D045744:Cell Line, Tumor / Q000473:pathology; D018031:Connexin 43 / Q000737:chemistry* / Q000235:genetics; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D009154:Mutation; D009447:Neuroblastoma / Q000473:pathology; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship; D014162:Transfection
D018031:Connexin 43; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins