PMID- 9251796
OWN - NLM
STAT- MEDLINE
DCOM- 19970929
LR  - 20231213
IS  - 0006-3495 (Print)
IS  - 1542-0086 (Electronic)
IS  - 0006-3495 (Linking)
VI  - 73
IP  - 2
DP  - 1997 Aug
TI  - Positive charges of the initial C-terminus domain of Cx32 inhibit gap junction 
      gating sensitivity to CO2.
PG  - 798-806
AB  - Gap junction channels close with CO2 exposure. To determine whether the 
      carboxy-terminus (CT) of connexin32 (Cx32) participates in gating, the CO2 
      sensitivity of channels made of Cx32 or Cx32 mutants was studied by double 
      voltage clamp. In Xanopus laevis oocytes expressing Cx32, junctional conductance 
      (Gj) dropped to 85% and 47% of controls with 3- and 15-min CO2 exposures, 
      respectively. In response to the 15-min exposure to CO2, pHi dropped to 
      approximately 6.4 in 5-7 min and did not decrease further, even with 30-min 
      exposures. CT deletion by 84% did not affect CO2 sensitivity, but replacement of 
      five arginines (R215, R219, R220, R223, and R224) with asparagines (N) or 
      threonines at the beginning of CT (CT1) in Cx32 or Cx32 deleted beyond residue 
      225 greatly enhanced CO2 sensitivity (with 3-min CO2 Gj dropped to approximately 
      8%). Partial R/N replacement resulted in intermediate CO2 sensitivity 
      enhancement. R215 is a stronger inhibitor than R219-220, whereas R223-224 may 
      diminish the inhibitory efficiency of R215 and R219-220. Therefore, positive 
      charges of CT1 reduce the CO2 sensitivity of Cx32, whereas the rest (> 80%) of CT 
      seems to play no role in CO2-induced gating. The role of presumed electrostatic 
      interactions among Cx32 domains in CO2-induced gating is discussed.
FAU - Wang, X G
AU  - Wang XG
AD  - Department of Pharmacology and Physiology, University of Rochester School of 
      Medicine and Dentistry, New York 14642-8711, USA.
FAU - Peracchia, C
AU  - Peracchia C
LA  - eng
GR  - GM20113/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biophys J
JT  - Biophysical journal
JID - 0370626
RN  - 0 (Connexins)
RN  - 0 (Recombinant Proteins)
RN  - 142M471B3J (Carbon Dioxide)
RN  - 7006-34-0 (Asparagine)
RN  - 94ZLA3W45F (Arginine)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Arginine
MH  - Asparagine
MH  - Base Sequence
MH  - Carbon Dioxide/*pharmacology
MH  - Connexins/biosynthesis/*chemistry/*physiology
MH  - Electric Conductivity
MH  - Female
MH  - Gap Junctions/drug effects/*physiology
MH  - Kinetics
MH  - Membrane Potentials
MH  - Molecular Sequence Data
MH  - Mutagenesis, Site-Directed
MH  - Oocytes/physiology
MH  - Recombinant Proteins/chemistry/metabolism
MH  - Time Factors
MH  - Xenopus laevis
MH  - Gap Junction beta-1 Protein
PMC - PMC1180976
EDAT- 1997/08/01 00:00
MHDA- 1997/08/01 00:01
PMCR- 1998/08/01
CRDT- 1997/08/01 00:00
PHST- 1997/08/01 00:00 [pubmed]
PHST- 1997/08/01 00:01 [medline]
PHST- 1997/08/01 00:00 [entrez]
PHST- 1998/08/01 00:00 [pmc-release]
AID - S0006-3495(97)78112-8 [pii]
AID - 10.1016/S0006-3495(97)78112-8 [doi]
PST - ppublish
SO  - Biophys J. 1997 Aug;73(2):798-806. doi: 10.1016/S0006-3495(97)78112-8.