title: Secondary structure formation of a transmembrane segment in Kv channels.
abstract: Transmembrane segments in the intact voltage-gated potassium (Kv) channel are helical. To ascertain whether this helicity could first be manifested inside the ribosomal tunnel, we generated biogenic peptide intermediates of Kv1.3 and mass-tagged the cysteine-scanned S6 transmembrane segment using pegylation (PEG-MAL) and calmodulation (CaM-MAL). For reference, we created an extended peptide that was used as a "molecular tape measure" of the ribosomal tunnel and determined that the functional length of the tunnel is 99-112 A. We demonstrate that the S6 segment forms a compact structure inside the ribosomal tunnel and that the N-terminal half of S6 compacts more than the C-terminal half of S6. These results bear on the earliest folding events during biogenesis of ion channels.
authors.affiliation: Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6085, USA.
authors.forename: Jianli
authors.initials: J
authors.lastname: Lu
authors.forename: Carol
authors.initials: C
authors.lastname: Deutsch
mesh_terms: D000595:Amino Acid Sequence; D002147:Calmodulin / Q000737:chemistry; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism; D051664:Kv1.3 Potassium Channel; D008301:Maleimides / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D011092:Polyethylene Glycols / Q000737:chemistry; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry* / Q000235:genetics; D017510:Protein Folding; D011499:Protein Processing, Post-Translational / Q000235:genetics; D017433:Protein Structure, Secondary / Q000235:genetics; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D002147:Calmodulin; D051664:Kv1.3 Potassium Channel; D008301:Maleimides; D008565:Membrane Proteins; D010446:Peptide Fragments; D024642:Potassium Channels, Voltage-Gated; D012269:Ribosomal Proteins; D011092:Polyethylene Glycols