Direct visualization of the trimeric structure of the ASIC1a channel, using AFM imaging.
There has been confusion about the subunit stoichiometry of the degenerin family of ion channels. Recently, a crystal structure of acid-sensing ion channel (ASIC) 1a revealed that it assembles as a trimer. Here, we used atomic force microscopy (AFM) to image unprocessed ASIC1a bound to mica. We detected a mixture of subunit monomers, dimers and trimers. In some cases, triple-subunit clusters were clearly visible, confirming the trimeric structure of the channel, and indicating that the trimer sometimes disaggregated after adhesion to the mica surface. This AFM-based technique will now enable us to determine the subunit arrangement within heteromeric ASICs.
Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK.
Stewart M
SM
Carnally
Harveer S
HS
Dev
Andrew P
AP
Stewart
Nelson P
NP
Barrera
Miguel X
MX
Van Bemmelen
Laurent
L
Schild
Robert M
RM
Henderson
J Michael
JM
Edwardson
D062565:Acid Sensing Ion Channels; D000538:Aluminum Silicates / Q000737:chemistry; D006801:Humans; D018625:Microscopy, Atomic Force; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D021122:Protein Subunits / Q000737:chemistry; D015222:Sodium Channels / Q000737:chemistry* / Q000648:ultrastructure*
C568266:ASIC1 protein, human; D062565:Acid Sensing Ion Channels; D000538:Aluminum Silicates; D009419:Nerve Tissue Proteins; D021122:Protein Subunits; D015222:Sodium Channels; C011934:mica