ADAM22, a Kv1 channel-interacting protein, recruits membrane-associated guanylate kinases to juxtaparanodes of myelinated axons.
Clustered Kv1 K(+) channels regulate neuronal excitability at juxtaparanodes of myelinated axons, axon initial segments, and cerebellar basket cell terminals (BCTs). These channels are part of a larger protein complex that includes cell adhesion molecules and scaffolding proteins. To identify proteins that regulate assembly, clustering, and/or maintenance of axonal Kv1 channel protein complexes, we immunoprecipitated Kv1.2 alpha subunits, and then used mass spectrometry to identify interacting proteins. We found that a disintegrin and metalloproteinase 22 (ADAM22) is a component of the Kv1 channel complex and that ADAM22 coimmunoprecipitates Kv1.2 and the membrane-associated guanylate kinases (MAGUKs) PSD-93 and PSD-95. When coexpressed with MAGUKs in heterologous cells, ADAM22 and Kv1 channels are recruited into membrane surface clusters. However, coexpression of Kv1.2 with ADAM22 and MAGUKs does not alter channel properties. Among all the known Kv1 channel-interacting proteins, only ADAM22 is found at every site where Kv1 channels are clustered. Analysis of Caspr-null mice showed that, like other previously described juxtaparanodal proteins, disruption of the paranodal junction resulted in redistribution of ADAM22 into paranodal zones. Analysis of Caspr2-, PSD-93-, PSD-95-, and double PSD-93/PSD-95-null mice showed ADAM22 clustering at BCTs requires PSD-95, but ADAM22 clustering at juxtaparanodes requires neither PSD-93 nor PSD-95. In direct contrast, analysis of ADAM22-null mice demonstrated juxtaparanodal clustering of PSD-93 and PSD-95 requires ADAM22, whereas Kv1.2 and Caspr2 clustering is normal in ADAM22-null mice. Thus, ADAM22 is an axonal component of the Kv1 K(+) channel complex that recruits MAGUKs to juxtaparanodes.
Ogawa
Yasuhiro
Y
Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA.
Oses-Prieto
Juan
J
Kim
Moon Young
MY
Horresh
Ido
I
Peles
Elior
E
Burlingame
Alma L
AL
Trimmer
James S
JS
Meijer
Dies
D
Rasband
Matthew N
MN
D051722:ADAM Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001369:Axons / Q000378:metabolism*; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D054351:Electrical Synapses / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000235:genetics; D051528:Guanylate Kinases / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051637:Shaker Superfamily of Potassium Channels / Q000378:metabolism; D016622:Silver Staining / Q000379:methods
D015816:Cell Adhesion Molecules, Neuronal; C491322:Cntnap1 protein, mouse; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C501451:Mpp2 protein, rat; D009419:Nerve Tissue Proteins; D051637:Shaker Superfamily of Potassium Channels; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D051528:Guanylate Kinases; D051722:ADAM Proteins; C121258:Adam22 protein, mouse