Guizhen Fan / Matthew L Baker / Zhao Wang / Mariah R Baker / Pavel A Sinyagovskiy / Wah Chiu / Steven J Ludtke / Irina I Serysheva /
PubMed Abstract
Inositol-1,4,5-trisphosphate receptors (InsP3Rs) are ubiquitous ion channels responsible for cytosolic Ca(2+) signalling and essential for a broad array of cellular processes ranging from contraction ...Inositol-1,4,5-trisphosphate receptors (InsP3Rs) are ubiquitous ion channels responsible for cytosolic Ca(2+) signalling and essential for a broad array of cellular processes ranging from contraction to secretion, and from proliferation to cell death. Despite decades of research on InsP3Rs, a mechanistic understanding of their structure-function relationship is lacking. Here we present the first, to our knowledge, near-atomic (4.7 Å) resolution electron cryomicroscopy structure of the tetrameric mammalian type 1 InsP3R channel in its apo-state. At this resolution, we are able to trace unambiguously ∼85% of the protein backbone, allowing us to identify the structural elements involved in gating and modulation of this 1.3-megadalton channel. Although the central Ca(2+)-conduction pathway is similar to other ion channels, including the closely related ryanodine receptor, the cytosolic carboxy termini are uniquely arranged in a left-handed α-helical bundle, directly interacting with the amino-terminal domains of adjacent subunits. This configuration suggests a molecular mechanism for allosteric regulation of channel gating by intracellular signals.
EMDB-6369, PDB-3jav: Structure of full-length IP3R1 channel in the apo-state determined by single particle cryo-EM Method: EM (single particle) / Resolution: 4.7 Å
Source
rattus norvegicus (Norway rat)
Keywords
TRANSPORT PROTEIN / inositol 1 / 4 / 5-trisphosphate receptor / calcium release channel / calcium signaling
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TRANSPORT PROTEIN / 
