Crystal structure of the C-terminal four-helix bundle of the potassium channel KCa3.1
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No Canadian affiliation. An affiliation-only frame — the usual design — would never have seen this work. It is one of the works that make the case for inverting the frame.
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Crystal structure of a potassium channel domain; structural biology.
The study reports a crystal structure and biological implications of a potassium channel.
Crystal structure of a potassium channel domain is structural biology domain research.
Abstract
KCa3.1 (also known as SK4 or IK1) is a mammalian intermediate-conductance potassium channel that plays a critical role in the activation of T cells, B cells, and mast cells, effluxing potassium ions to maintain a negative membrane potential for influxing calcium ions. KCa3.1 shares primary sequence similarity with three other (low-conductance) potassium channels: KCa2.1, KCa2.2, and KCa2.3 (also known as SK1-3). These four homotetrameric channels bind calmodulin (CaM) in the cytoplasmic region, and calcium binding to CaM triggers channel activation. Unique to KCa3.1, activation also requires phosphorylation of a single histidine residue, His358, in the cytoplasmic region, which relieves copper-mediated inhibition of the channel. Near the cytoplasmic C-terminus of KCa3.1 (and KCa2.1-2.3), secondary-structure analysis predicts the presence of a coiled-coil/heptad repeat. Here, we report the crystal structure of the C-terminal coiled-coil region of KCa3.1, which forms a parallel four-helix bundle, consistent with the tetrameric nature of the channel. Interestingly, the four copies of a histidine residue, His389, in an 'a' position within the heptad repeat, are observed to bind a copper ion along the four-fold axis of the bundle. These results suggest that His358, the inhibitory histidine in KCa3.1, might coordinate a copper ion through a similar binding mode.
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The record
- Venue
- PLoS ONE
- Topic
- Ion channel regulation and function
- Field
- Biochemistry, Genetics and Molecular Biology
- Canadian institutions
- —
- Funders
- National Institute of Allergy and Infectious DiseasesNational Institute of General Medical SciencesSchool of Medicine, New York UniversityYork University
- Keywords
- Potassium channelChemistryCalcium-activated potassium channelHistidineIon channelBiophysicsBK channelHelix bundleCrystallographyCalmodulinProtein structureBiochemistryBiologyAmino acidReceptor
- Has abstract in OpenAlex
- yes