Am J Physiol 1998 Nov 01;2755:C1384-90. doi: 10.1152/ajpcell.1998.275.5.C1384.

Molecular dissection of a basic COOH-terminal domain of Cx32 that inhibits gap junction gating sensitivity.

???displayArticle.abstract???
Connexin32 (Cx32) mutants were studied by double voltage clamp in Xenopus oocytes to determine the role of basic COOH-terminal residues in gap junction channel gating by CO2 and transjunctional voltage. Replacement of five arginines with N (5R/N) or T residues in the initial COOH-terminal domain (CT1) of Cx32 enhanced CO2 sensitivity. The positive charge, rather than the R residue per se, is responsible for the inhibitory role of CT1, because mutants replacing the five R residues with K (5R/K) or H (5R/H) displayed CO2 sensitivity comparable to that of wild-type Cx32. Mutants replacing R with N residues four at a time (4R/N) showed that CO2 sensitivity is strongly inhibited by R215 and mildly by R219, whereas R220, R223, and R224 may slightly increase sensitivity. Neither the 5R/N nor the 4R/N mutants differed in voltage sensitivity from wild-type Cx32. The possibility that inhibition of gating sensitivity results from electrostatic interactions between CT1 and the cytoplasmic loop is discussed as part of a model that envisions the cytoplasmic loop of Cx32 as a key element of chemical gating.

???displayArticle.pubmedLink??? 9814988
???displayArticle.link??? Am J Physiol
???displayArticle.grants??? [+]

Species referenced: Xenopus laevis
Genes referenced: ctf1 gjb1