Biophysical Journal 73: 798-806 (1997)
© 1997 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wang, X G Articles by Peracchia, C Search for Related Content PubMed PubMed Citation Articles by Wang, X G Articles by Peracchia, C

Positive charges of the initial C-terminus domain of Cx32 inhibit gap junction gating sensitivity to CO2.

Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, New York 14642-8711, USA.

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.

This article has been cited by other articles:

				L. Tao and A. L. Harris Biochemical Requirements for Inhibition of Connexin26-containing Channels by Natural and Synthetic Taurine Analogs J. Biol. Chem., September 10, 2004; 279(37): 38544 - 38554. [Abstract] [Full Text] [PDF]

				T. W. White, M. Srinivas, H. Ripps, A. Trovato-Salinaro, D. F. Condorelli, and R. Bruzzone Virtual cloning, functional expression, and gating analysis of human connexin31.9 Am J Physiol Cell Physiol, September 1, 2002; 283(3): C960 - C970. [Abstract] [Full Text] [PDF]

				C. Peracchia, X. G. Wang, and L. L. Peracchia Is the chemical gate of connexins voltage sensitive? Behavior of Cx32 wild-type and mutant channels Am J Physiol Cell Physiol, June 1, 1999; 276(6): C1361 - C1373. [Abstract] [Full Text] [PDF]

				C. G. Bevans and A. L. Harris Regulation of Connexin Channels by pH. DIRECT ACTION OF THE PROTONATED FORM OF TAURINE AND OTHER AMINOSULFONATES J. Biol. Chem., February 5, 1999; 274(6): 3711 - 3719. [Abstract] [Full Text] [PDF]

				Y Landesman, T. White, T. Starich, J. Shaw, D. Goodenough, and D. Paul Innexin-3 forms connexin-like intercellular channels J. Cell Sci., January 7, 1999; 112(14): 2391 - 2396. [Abstract] [PDF]

				X. G. Wang and C. Peracchia Molecular dissection of a basic COOH-terminal domain of Cx32 that inhibits gap junction gating sensitivity Am J Physiol Cell Physiol, November 1, 1998; 275(5): C1384 - C1390. [Abstract] [Full Text] [PDF]

				C. Ressot, D. Gomes, A. Dautigny, D. Pham-Dinh, and R. Bruzzone Connexin32 Mutations Associated with X-Linked Charcot-Marie-Tooth Disease Show Two Distinct Behaviors: Loss of Function and Altered Gating Properties J. Neurosci., June 1, 1998; 18(11): 4063 - 4075. [Abstract] [Full Text] [PDF]

				C. Peracchia, A. Sotkis, X. G. Wang, L. L. Peracchia, and A. Persechini Calmodulin Directly Gates Gap Junction Channels J. Biol. Chem., August 18, 2000; 275(34): 26220 - 26224. [Abstract] [Full Text] [PDF]