Molecular interaction and functional regulation of connexin50 gap junctions by calmodulin

被引：41

作者：

Chen, Yanyi ^{[1
]}

Zhou, Yubin ^{[1
]}

Lin, Xianming ^{[2
]}

Wong, Hing-Cheung ^{[1
]}

Xu, Qin ^{[2
]}

Jiang, Jie ^{[1
]}

Wang, Siming ^{[1
]}

Lurtz, Monica M. ^{[3
]}

Louis, Charles F. ^{[3
]}

Veenstra, Richard D. ^{[2
]}

Yang, Jenny J. ^{[1
]}

机构：

[1] Georgia State Univ, Dept Chem, Atlanta, GA 30303 USA

[2] SUNY Upstate Med Univ, Dept Pharmacol, Syracuse, NY 12210 USA

[3] Univ Calif Riverside, Dept Cell Biol & Neurosci, Riverside, CA 92521 USA

来源：

BIOCHEMICAL JOURNAL | 2011年 / 435卷

基金：

美国国家卫生研究院;

关键词：

calcium; calmodulin; connexin50; gap junction; junctional conductance; protein-protein interaction; EMPIRICAL PARAMETERS; BINDING-PROTEINS; FOLDING PROBLEM; TOPOLOGY PREDICTION; NMR-SPECTROSCOPY; CALCIUM-BINDING; CHANNELS; DOMAIN; PEPTIDES; IDENTIFICATION;

D O I：

10.1042/BJ20101726

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Cx50 (connexin50), a member of the alpha-family of gap junction proteins expressed in the lens of the eye, has been shown to be essential for normal lens development. In the present study, we identified a CaMBD [CaM (calmodulin)-binding domain] (residues 141-166) in the intracellular loop of Cx50. Elevations in intracellular Ca2+ concentration effected a 95 % decline in g(j) (junctional conductance) of Cx50 in N2a cells that is likely to be mediated by CaM, because inclusion of the CaM inhibitor calmidazolium prevented this Ca2+-dependent decrease in g(j). The direct involvement of the Cx50 CaMBD in this Ca2+/CaM-dependent regulation was demonstrated further by the inclusion of a synthetic peptide encompassing the CaMBD in both whole-cell patch pipettes, which effectively prevented the intracellular Ca2+-dependent decline in g(j). Biophysical studies using NMR and fluorescence spectroscopy reveal further that the peptide stoichiometrically binds to Ca2+/CaM with an affinity of similar to 5 nM. The binding of the peptide expanded the Ca2+-sensing range of CaM by increasing the Ca2+ affinity of the C-lobe of CaM, while decreasing the Ca2+ affinity of the N-lobe of CaM. Overall, these results demonstrate that the binding of Ca2+/CaM to the intracellular loop of Cx50 is critical for mediating the Ca2+-dependent inhibition of Cx50 gap junctions in the lens of the eye.

引用

页码：711 / 722

页数：12

共 60 条

[1] Assembly of gap junction channels - Mechanism, effects of calmodulin antagonists and identification of connexin oligomerization determinants [J].