Formation of the gap junction intercellular channel requires a 30° rotation for interdigitating two apposing connexons

The need for molecular heterogeneity of gap junction channel proteins in vivo has been enigmatic. Recently, functional replacement of one channel gene with another in mice and flies has revealed that cellular health depends not simply on gap junction communication but also requires the correct type of intercellular channel subunit.

Download Full-text

Three-Dimensional Structure of the Gap Junction Connexon and Intercellular Channel

Microscopy and Microanalysis ◽

10.1017/s1431927600008023 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 227-228

Author(s):

Guy Perkins ◽

Dan Goodenough ◽

Gina Sosinsky

Keyword(s):

Small Molecules ◽

Gap Junction ◽

Three Dimensional ◽

Surface Topology ◽

Dimensional Structure ◽

Cell Contact ◽

Membrane Channels ◽

Membrane Channel ◽

Contact Areas ◽

Intercellular Channel

Gap junctions are specialized cell-cell contact areas by which cells communication with each other. Within these contact areas are tens to thousands of membrane channels. A gap junction membrane channel (also referred to as an intercellular channel) is unique among membrane channels in that it is composed of two oligomers with each of two adjacent tissue cells contributing one oligomer (called a connexon or hemichannel). The pore of the intercellular channel controls the passage of small molecules and ions from one cell to another.We are interested in how the structure and surface topology of the gap junction connexon at its extracellular surface influences the docking and formation of an intercellular communicating channel. It has been demonstrated that connexons made from some connexins will dock and form functional channels with some but not all connexons made from other isoforms. This selectivity is surprising considering that the primary sequences of the docking domains are highly conserved.

Download Full-text

The Nature of the Intramembrane Particle

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600003020 ◽

1980 ◽

Vol 38 ◽

pp. 688-691

Author(s):

A.J. Verkleij

Keyword(s):

Escherichia Coli ◽

Tight Junction ◽

Gap Junction ◽

The Other ◽

Fracture Face ◽

Band 3 Protein ◽

Satisfactory Explanation ◽

Freeze Fracturing ◽

Intramembrane Particle ◽

Luminal Membrane

Freeze-fracturing splits membranes into two helves, thus allowing an examination of the membrane interior. The 5-10 rm particles visible on both monolayers are widely assumed to be proteinaceous in nature. Most membranes do not reveal impressions complementary to particles on the opposite fracture face, if the membranes are fractured under conditions without etching. Even if it is considered that shadowing, contamination or fracturing itself might obscure complementary pits', there is no satisfactory explanation why under similar physical circimstances matching halves of other membranes can be visualized. A prominent example of uncomplementarity is found in the erythrocyte manbrane. It is wall established that band 3 protein and possibly glycophorin represents these nonccmplanentary particles. On the other hand a number of membrane types show pits opposite the particles. Scme well known examples are the ";gap junction',"; tight junction, the luminal membrane of the bladder epithelial cells and the outer membrane of Escherichia coli.

Download Full-text