Differential interaction of voltage-gated K+ channel beta-subunits with cytoskeleton is mediated by unique amino terminal domains.
To define the molecular characteristics of K+ channel beta-subunit polypeptides, we have studied their biochemical properties and subcellular distribution in transfected mammalian cells. We find that the recombinant voltage-dependent K+ (Kv) beta1.1 and Kvbeta2 polypeptides have distinct detergent solubility properties owing to a novel association of Kvbeta1.1 with the actin-based cytoskeleton. Mutational and chimeric protein analyses show that the unique aminoterminus of Kvbeta1.1 is both necessary and sufficient for mediating the association of beta-subunits with cytoskeleton. Thus, the interaction with cytoskeleton is mediated through the amino-terminal domain previously shown to be necessary for modulating alpha-subunit inactivation, but not necessary for interaction with alpha-subunit polypeptides. These data reveal that different domains of beta-subunit polypeptides mediate interactions with cytoskeleton and with alpha-subunits, and provide a structural basis for previous reports that linked the extent of beta-subunit-induced inactivation to the state of the actin cytoskeleton.
Nakahira
K
K
Department of Biochemistry and Cell Biology and Institute for Cell and Developmental Biology, State University of New York at Stony Brook, 11794-5215, USA.
Matos
M F
MF
Trimmer
J S
JS
D000199:Actins / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D003902:Detergents / Q000494:pharmacology; D007150:Immunohistochemistry; D010446:Peptide Fragments / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D015221:Potassium Channels / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D020033:Protein Isoforms / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism; D017384:Sequence Deletion; D012995:Solubility / Q000187:drug effects; D014162:Transfection
D000199:Actins; D003902:Detergents; D010446:Peptide Fragments; D015221:Potassium Channels; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins