I SA channel complexes include four subunits each of DPP6 and Kv4.2.
Kv4 potassium channels produce rapidly inactivating currents that regulate excitability of muscles and nerves. To reconstitute the neuronal A-type current I(SA), Kv4 subunits assemble with DPP6, a single transmembrane domain accessory subunit. DPP6 alters function-accelerating activation, inactivation, and recovery from inactivation-and increases surface expression. We sought here to determine the stoichiometry of Kv4 and DPP6 in complexes using functional and biochemical methods. First, wild type channels formed from subunit monomers were compared with channels carrying subunits linked in tandem to enforce 4:4 and 4:2 assemblies (Kv4.2-DPP6 and Kv4.2-Kv4.2-DPP6). Next, channels were overexpressed and purified so that the molar ratio of subunits in complexes could be assessed by direct amino acid analysis. Both biophysical and biochemical methods indicate that I(SA) channels carry four subunits each of Kv4.2 and DPP6.
Soh
Heun
H
Department of Pediatrics and Institute for Molecular Pediatric Sciences, Pritzker School of Medicine, Biological Sciences Division, University of Chicago, Chicago, IL 60637, USA.
Goldstein
Steve A N
SA
D000818:Animals; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D006801:Humans; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D020836:Protein Structure, Quaternary / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D051672:Shal Potassium Channels / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D051672:Shal Potassium Channels; C503535:DPP6 protein, human; D010447:Peptide Hydrolases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases