Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Positive charges of the initial C-terminus domain of Cx32 inhibit gap junction gating sensitivity to CO2.
Wang XG
,
Peracchia C
.
???displayArticle.abstract???
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.
Armstrong,
Time course of TEA(+)-induced anomalous rectification in squid giant axons.
1966, Pubmed
Armstrong,
Time course of TEA(+)-induced anomalous rectification in squid giant axons.
1966,
Pubmed
Barrio,
Gap junctions formed by connexins 26 and 32 alone and in combination are differently affected by applied voltage.
1991,
Pubmed
,
Xenbase
Bruzzone,
Connections with connexins: the molecular basis of direct intercellular signaling.
1996,
Pubmed
Ek-Vitorín,
PH regulation of connexin43: molecular analysis of the gating particle.
1996,
Pubmed
,
Xenbase
Lazrak,
Gap junction gating sensitivity to physiological internal calcium regardless of pH in Novikoff hepatoma cells.
1993,
Pubmed
Liu,
A structural basis for the unequal sensitivity of the major cardiac and liver gap junctions to intracellular acidification: the carboxyl tail length.
1993,
Pubmed
,
Xenbase
Morley,
Intramolecular interactions mediate pH regulation of connexin43 channels.
1996,
Pubmed
,
Xenbase
Paul,
Molecular cloning of cDNA for rat liver gap junction protein.
1986,
Pubmed
Peracchia,
Increase in gap junction resistance with acidification in crayfish septate axons is closely related to changes in intracellular calcium but not hydrogen ion concentration.
1990,
Pubmed
Peracchia,
Effects of caffeine and ryanodine on low pHi-induced changes in gap junction conductance and calcium concentration in crayfish septate axons.
1990,
Pubmed
Peracchia,
Inhibition of calmodulin expression prevents low-pH-induced gap junction uncoupling in Xenopus oocytes.
1996,
Pubmed
,
Xenbase
Pressler,
Intracellular pH and cell-to-cell transmission in sheep Purkinje fibers.
1989,
Pubmed
Rabadan-Diehl,
A connexin-32 mutation associated with Charcot-Marie-Tooth disease does not affect channel formation in oocytes.
1994,
Pubmed
Spray,
Equilibrium properties of a voltage-dependent junctional conductance.
1981,
Pubmed
,
Xenbase
Spray,
Structure-activity relations of the cardiac gap junction channel.
1990,
Pubmed
Turin,
Carbon dioxide reversibly abolishes ionic communication between cells of early amphibian embryo.
1977,
Pubmed
,
Xenbase
Wang,
Connexin 32/38 chimeras suggest a role for the second half of inner loop in gap junction gating by low pH.
1996,
Pubmed
,
Xenbase
Wang,
Chimeric evidence for a role of the connexin cytoplasmic loop in gap junction channel gating.
1996,
Pubmed
,
Xenbase
Werner,
Gating properties of connexin32 cell-cell channels and their mutants expressed in Xenopus oocytes.
1991,
Pubmed
,
Xenbase
Zagotta,
Restoration of inactivation in mutants of Shaker potassium channels by a peptide derived from ShB.
1990,
Pubmed
,
Xenbase
