Molecular interaction and functional regulation of connexin50 gap junctions by calmodulin. Academic Article uri icon

abstract

  • Cx50 (connexin50), a member of the -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 gj (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 gj. 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 gj. Biophysical studies using NMR and fluorescence spectroscopy reveal further that the peptide stoichiometrically binds to Ca2+/CaM with an affinity of ~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.

published proceedings

  • Biochem J

altmetric score

  • 6

author list (cited authors)

  • Chen, Y., Zhou, Y., Lin, X., Wong, H., Xu, Q., Jiang, J., ... Yang, J. J.

citation count

  • 41

complete list of authors

  • Chen, Yanyi||Zhou, Yubin||Lin, Xianming||Wong, Hing-Cheung||Xu, Qin||Jiang, Jie||Wang, Siming||Lurtz, Monica M||Louis, Charles F||Veenstra, Richard D||Yang, Jenny J

publication date

  • May 2011