Biogenesis of the T1-S1 linker of voltage-gated K+ channels.
In the model derived from the crystal structure of Kv1.2, a six-transmembrane voltage-gated potassium channel, the linker between a cytosolic tetramerization domain, T1, and the first transmembrane segment, S1, is projected radially outward from the channel's central axis. This T1-S1 linker was modeled as two polyglycine helices to accommodate the residues between T1 and S1 [Long et al. (2005) Science 309, 897-903]; however, the structure of this linker is not known. Here, we investigate whether a compact secondary structure of the T1-S1 linker exists at an early stage of Kv channel biogenesis. We have used a mass-tagging accessibility assay to report the biogenesis of secondary structure for three consecutive regions of Kv1.3, a highly homologous isoform of Kv1.2. The three regions include the T1-S1 linker and its two flanking regions, alpha5 of the T1 domain and S1. Both alpha5 and S1 manifest compact structures (helical) inside the ribosomal exit tunnel, whereas the T1-S1 linker does not. Moreover, the location of the peptide in the tunnel influences compaction.
Tu
LiWei
L
Department of Physiology, University of Pennsylvania, Philadelpha, Pennsylvania 19104-6085, USA.
Wang
Jing
J
Deutsch
Carol
C
D000595:Amino Acid Sequence; D001704:Biopolymers; D004591:Electrophoresis, Polyacrylamide Gel; D015640:Ion Channel Gating; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry / Q000502:physiology*; D017433:Protein Structure, Secondary
D001704:Biopolymers; D015221:Potassium Channels