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Dissecting Key Determinants For Calcium And Calmodulin Regulation Of Gap Junction And Viral Protein, Yanyi Chen

Chemistry Dissertations

Calcium and calmodulin are implicated in mediating the Ca²⁺-dependent regulation of gap junctions that are essential for the intercellular transmission of molecules such as nutrients, metabolites, metal ions and signal messengers (< 1000 Da) through its specialized cell membrane channels and communication to extracellular environment. To understand the key determinants for calcium and calmodulin regulation of gap junction, in this study, we identified a calmodulin binding domain in the second half of the intracellular loop of Cxonnexin50 (the major gap junction protein found in an eye lens) using peptide fragments that encompass predicted CaM binding sites and various biophysical methods. Our study provides the first direct evidence that CaM binds to a specific region of the ubiquitous gap junction protein Cx50 in a Ca²⁺-dependent manner. Furthermore, two novel CaM binding regions in cytosolic loop and C-termini of Connexin43 (the most ubiquitous connexin) have been shown to interact with CaM with different binding modes in the presence of Ca²⁺ using high resolution NMR. Our results also elucidate the molecular determinants of regulation of gap junction by multiple CaM targeting regions and provide insight into the molecular basis of …