Molecular Modeling Suggests Homologous 2-APB Binding Sites in Connexins 26 and 32

Abstract

Connexins are the transmembrane pore forming proteins that participate in gap junctions; connections between cells that certain nutrients and other molecules can pass through. There are several kinds of connexins (Cx) named based on their weight in kilodaltons. 2-aminoethoxydiphenyl borate (2-APB) is a small molecule inhibitor (SMI) of Cx26 and Cx32. Knock out of Cx32 and also blockage of Cx32 by 2-aminoethoxydiphenyl (2-APB) has been suspected to be beneficial in not only, drug induced liver toxicity, but also in blocking the propagation of an inflammatory signal. If the binding site of 2-APB can be determined, virtual screening for additional, perhaps more specific Cx26 and Cx32 blocking SMI can be carried out. Our modeling suggests that 2-APB binds to similar sites inside the pores of Cx26 and Cx32. Here 2-APB interacts with the conserved ILE82 and THR86. These residues hold the same numbering in both CX26 and CX32. This suggests these residues have a high level of conservation and importance Further virtual screening results imply molecules with similar activity on Cx26 and Cx32 as 2-APB can be found.\n\nBackground2-APB has been shown to block Cx26 and Cx32.\n\nResultsDocking of 2-APB to Cx26 and CX32 finds conserved binding site in pore. Suggestive that 2-APB has conserved homologous binding site on Cx26 and Cx32.\n\nConclusionMutational studies of 2APB and ILE82 and THR86 in Cx26 and Cx32 appear warranted. Additional virtual screening could yield 2-APB analogs that act on Cx26 and Cx32.\n\nSignificancePotential for developing gap junction blocking compounds.