Gap junction protein connexin-43 interacts directly with microtubules

Curr Biol. 2001 Sep 4;11(17):1364-8. doi: 10.1016/s0960-9822(01)00424-9.

Abstract

Gap junctions are specialized cell-cell junctions that mediate intercellular communication. They are composed of connexin proteins, which form transmembrane channels for small molecules [1, 2]. The C-terminal tail of connexin-43 (Cx43), the most widely expressed connexin member, has been implicated in the regulation of Cx43 channel gating by growth factors [3-5]. The Cx43 tail contains various protein interaction sites, but little is known about binding partners. To identify Cx43-interacting proteins, we performed pull-down experiments using the C-terminal tail of Cx43 fused to glutathione-S-transferase. We find that the Cx43 tail binds directly to tubulin and, like full-length Cx43, sediments with microtubules. Tubulin binding to Cx43 is specific in that it is not observed with three other connexins. We established that a 35-amino acid juxtamembrane region in the Cx43 tail, which contains a presumptive tubulin binding motif, is necessary and sufficient for microtubule binding. Immunofluorescence and immunoelectron microscopy studies reveal that microtubules extend to Cx43-based gap junctions in contacted cells. However, intact microtubules are dispensable for the regulation of Cx43 gap-junctional communication. Our findings suggest that, in addition to its well-established role as a channel-forming protein, Cx43 can anchor microtubule distal ends to gap junctions and thereby might influence the properties of microtubules in contacted cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Cell Line
  • Chlorocebus aethiops
  • Connexin 43 / genetics
  • Connexin 43 / metabolism*
  • Dogs
  • Humans
  • Microtubules / metabolism*
  • Molecular Sequence Data
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Tubulin / metabolism

Substances

  • Connexin 43
  • Recombinant Fusion Proteins
  • Tubulin