Expression, Purification, and Nanodisc Reconstitution of Connexin-43 Hemichannels for Structural Characterization by Cryo-Electron Microscopy

Abstract

Connexins are polytopic domain membrane proteins that form hexameric hemichannels (HCs) which can assemble into gap junction channels (GJCs) at the interface of two neighboring cells. The HCs may be involved in ion and small-molecule transport across the cellular plasma membrane in response to various stimuli. Despite their importance, relatively few structures of connexin HCs are available to date, compared to the structures of the GJCs. Here, we describe a protocol for expression, purification, and nanodisc reconstitution of connexin-43 (Cx43) HCs, which we have recently structurally characterized using cryo-EM analysis. Application of similar protocols to other connexin family members will lead to breakthroughs in the understanding of the structure and function of connexin HCs.

Keywords: Connexin-43; Cryo-EM; Gap junction channel; Hemichannel; Nanodisc; Reconstitution; Single-particle analysis.