title: NAB domain is essential for the subunit assembly of both alpha-alpha and alpha-beta complexes of shaker-like potassium channels.
abstract: There are at least five subfamilies of Shaker-like K+ channels. The diverse function of K+ channels are thought to be further modulated by hydrophilic beta subunits. Here we report that Kv beta 1 inactivates RCK4 and Shaker B K+ channels of the Kv1 subfamily, but not Shal2 of the Kv4 subfamily. This correlates the subfamily-specific bindings of Kv beta 1 to the cytoplasmic N-terminal domains of Kv1 alpha subunits. We map the Kv beta 1-binding site to a region overlapping NABKv1, a domain that specifies different Kv1 alpha subunits to form heterotetramers. Using chimeric alpha subunits, we demonstrate that NABKv1 is essential for the Kv beta 1-mediated inactivation. These results suggest that Kv beta 1 modulates a subset of K+ channels through the specific assembly of alpha-beta complexes and reveal the dual function of the NAB domain in mediating the assembly of both alpha-alpha and alpha-beta complexes.
authors.affiliation: Department of Physiology, School of Medicine, Johns Hopkins University Baltimore, Maryland 21205, USA.
authors.forename: W
authors.initials: W
authors.lastname: Yu
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: M
authors.initials: M
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002678:Chimera; D004330:Drosophila / Q000235:genetics*; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D018408:Patch-Clamp Techniques; D010449:Peptide Mapping; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
chemical_list: D015335:Molecular Probes; D015221:Potassium Channels