Electronic Thesis and Dissertation Repository


Master of Science




Dr. Donglin Bai


Gap junction (GJ) channels mediate direct intercellular communication. Each GJ channel consists of two hemichannels and each hemichannel is a hexamer of connexins. GJs formed by different connexins display different unitary channel conductance (γj) and intracellular magnesium modulation. The underlying mechanisms are not fully clear. The present study investigates the effect of mutating putative pore-lining residues (G8, G46, and V53 individually or together) into glutamate in Cx50 on homotypic GJ channel properties. Expression of the triple and individual mutants in GJ-deficient N2A cells resulted in the formation of functional GJ channels similar to that of Cx50 GJs. However, the γjs of G8EG46EV53E, G8E, G46E, but not V53E, GJs significantly increased Cx50 GJ γj. Increasing intracellular magnesium concentration from 0 to 3 mM significantly reduced the γjs of Cx50 and all mutant GJs. These results and our homology structural model indicate that these residues are likely pore-lining.