Higher order structure of aquaporin-4.
Unlike other mammalian AQPs, multiple tetramers of AQP4 associate in the plasma membrane to form peculiar structures called Orthogonal Arrays of Particles (OAPs), that are observable by freeze-fracture electron microscopy (FFEM). However, FFEM cannot give information about the composition of OAPs of different sizes, and due to its technical complexity is not easily applicable as a routine technique. Recently, we employed the 2D gel electrophoresis BN-SDS/PAGE that for the first time enabled the biochemical isolation of AQP4-OAPs from several tissues. We found that AQP4 protein is present in several higher-order complexes (membrane pools of supra-structures) which contain different ratios of M1/M23 isoforms corresponding to AQP4-OAPs of different size. In this paper, we illustrate in detail the potentiality of 2D BN/SDS-PAGE for analyzing AQP4 supra-structures, their relationship with the dystrophin glycoprotein complex and other membrane proteins, and their role as a specific target of Neuromyelitis Optica autoantibodies.
Nicchia
G P
GP
Department of General and Environmental Physiology and Centre of Excellence in Comparative Genomics CEGBA, University of Bari, I-70126 Bari, Italy.
Rossi
A
A
Mola
M G
MG
Pisani
F
F
Stigliano
C
C
Basco
D
D
Mastrototaro
M
M
Svelto
M
M
Frigeri
A
A
D000818:Animals; D051401:Aquaporin 4 / Q000737:chemistry* / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism; D001323:Autoantibodies / Q000737:chemistry / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D016189:Dystrophin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009471:Neuromyelitis Optica / Q000276:immunology; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D051381:Rats
C496031:Aqp4 protein, mouse; C496032:Aqp4 protein, rat; D051401:Aquaporin 4; D001323:Autoantibodies; D016189:Dystrophin; D008565:Membrane Proteins; D020033:Protein Isoforms; C085339:apo-dystrophin 1