7tdh
From Proteopedia
Rabbit RyR1 with AMP-PCP and high Ca2+ embedded in nanodisc in open conformation
Structural highlights
Function[RYR1_RABIT] Calcium channel that mediates the release of Ca(2+) from the sarcoplasmic reticulum into the cytoplasm and thereby plays a key role in triggering muscle contraction following depolarization of T-tubules. Repeated very high-level exercise increases the open probability of the channel and leads to Ca(2+) leaking into the cytoplasm. Can also mediate the release of Ca(2+) from intracellular stores in neurons, and may thereby promote prolonged Ca(2+) signaling in the brain. Required for normal embryonic development of muscle fibers and skeletal muscle. Required for normal heart morphogenesis, skin development and ossification during embryogenesis (By similarity).[1] [2] Publication Abstract from PubMedActivation of the intracellular Ca(2+) channel ryanodine receptor (RyR) triggers a cytosolic Ca(2+) surge, while elevated cytosolic Ca(2+) inhibits the channel in a negative feedback mechanism. Cryo-EM of rabbit RyR1 embedded in nanodiscs under partially inactivating Ca(2+) conditions revealed an open and a closed-inactivated conformation. Ca(2+) binding to the high affinity site engages the central and C-terminal domains into a block, which pries the S6 four-helix bundle open. Further rotation of this block pushes S6 toward the central axis, closing (inactivating) the channel. Main characteristics of the Ca(2+)-inactivated conformation are downward conformation of the cytoplasmic assembly and tightly-knit subunit interface contributed by a fully occupied Ca(2+) activation site, two inter-subunit resolved lipids, and two salt bridges between the EF hand domain and the S2-S3 loop validated by disease-causing mutations. The structural insight illustrates the prior Ca(2+) activation prerequisite for Ca(2+) inactivation and provides for seamless transition from inactivated to closed conformations. Ca(2+)-inactivation of the mammalian ryanodine receptor type 1 in a lipidic environment revealed by cryo-EM.,Nayak AR, Samso M Elife. 2022 Mar 8;11. pii: 75568. doi: 10.7554/eLife.75568. PMID:35257661[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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