scholarly journals Probing the Role of Negatively Charged Amino Acid Residues in Ion Permeation of Skeletal Muscle Ryanodine Receptor

2005 ◽  
Vol 89 (1) ◽  
pp. 256-265 ◽  
Author(s):  
Ying Wang ◽  
Le Xu ◽  
Daniel A. Pasek ◽  
Dirk Gillespie ◽  
Gerhard Meissner
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Ryanodine Receptor ◽  
Ion Permeation ◽  
Amino Acid Residues

scholarly journals A central core disease mutation in the Ca2+-binding site of skeletal muscle ryanodine receptor impairs single-channel regulation

2019 ◽  
Vol 317 (2) ◽  
pp. C358-C365 ◽  
Author(s):  
Venkat R. Chirasani ◽  
Le Xu ◽  
Hannah G. Addis ◽  
Daniel A. Pasek ◽  
Nikolay V. Dokholyan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Missense Mutation ◽  
Ryanodine Receptor ◽  
Single Channel ◽  
Central Core ◽  
Central Core Disease ◽  
Hek293 Cells ◽  
Amino Acid Residues ◽  
Single Channel Recordings

Cryoelectron microscopy and mutational analyses have shown that type 1 ryanodine receptor (RyR1) amino acid residues RyR1-E3893, -E3967, and -T5001 are critical for Ca2+-mediated activation of skeletal muscle Ca2+ release channel. De novo missense mutation RyR1-Q3970K in the secondary binding sphere of Ca2+ was reported in association with central core disease (CCD) in a 2-yr-old boy. Here, we characterized recombinant RyR1-Q3970K mutant by cellular Ca2+ release measurements, single-channel recordings, and computational methods. Caffeine-induced Ca2+ release studies indicated that RyR1-Q3970K formed caffeine-sensitive, Ca2+-conducting channel in HEK293 cells. However, in single-channel recordings, RyR1-Q3970K displayed low Ca2+-dependent channel activity and greatly reduced activation by caffeine or ATP. A RyR1-Q3970E mutant corresponds to missense mutation RyR2-Q3925E associated with arrhythmogenic syndrome in cardiac muscle. RyR1-Q3970E also formed caffeine-induced Ca2+ release in HEK293 cells and exhibited low activity in the presence of the activating ligand Ca2+ but, in contrast to RyR1-Q3970K, was activated by ATP and caffeine in single-channel recordings. Computational analyses suggested distinct structural rearrangements in the secondary binding sphere of Ca2+ of the two mutants, whereas the interaction of Ca2+ with directly interacting RyR1 amino acid residues Glu3893, Glu3967, and Thr5001 was only minimally affected. We conclude that RyR1-Q3970 has a critical role in Ca2+-dependent activation of RyR1 and that a missense RyR1-Q3970K mutant may give rise to myopathy in skeletal muscle.

scholarly journals Amino Acid Residues 4425–4621 Localized on the Three-Dimensional Structure of the Skeletal Muscle Ryanodine Receptor

2000 ◽  
Vol 78 (3) ◽  
pp. 1349-1358 ◽  
Author(s):  
Brenda L. Benacquista ◽  
Manjuli R. Sharma ◽  
Montserrat Samsó ◽  
Francesco Zorzato ◽  
Susan Treves ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Ryanodine Receptor ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Amino Acid Residues ◽  
Three Dimensional Structure

scholarly journals Deletion of the Actin-Associated Tropomyosin Tpm3 Leads to Reduced Cell Complexity in Cultured Hippocampal Neurons—New Insights into the Role of the C-Terminal Region of Tpm3.1

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 715
Author(s):  
Tamara Tomanić ◽  
Claire Martin ◽  
Holly Stefen ◽  
Esmeralda Parić ◽  
Peter Gunning ◽  
...  
Keyword(s):  
Amino Acid ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Growth Cones ◽  
Amino Acid Residues ◽  
Terminal Amino Acid ◽  
C Terminus ◽  
Primary Mouse ◽  
Terminal Amino

Tropomyosins (Tpms) have been described as master regulators of actin, with Tpm3 products shown to be involved in early developmental processes, and the Tpm3 isoform Tpm3.1 controlling changes in the size of neuronal growth cones and neurite growth. Here, we used primary mouse hippocampal neurons of C57/Bl6 wild type and Bl6Tpm3flox transgenic mice to carry out morphometric analyses in response to the absence of Tpm3 products, as well as to investigate the effect of C-terminal truncation on the ability of Tpm3.1 to modulate neuronal morphogenesis. We found that the knock-out of Tpm3 leads to decreased neurite length and complexity, and that the deletion of two amino acid residues at the C-terminus of Tpm3.1 leads to more detrimental changes in neurite morphology than the deletion of six amino acid residues. We also found that Tpm3.1 that lacks the 6 C-terminal amino acid residues does not associate with stress fibres, does not segregate to the tips of neurites, and does not impact the amount of the filamentous actin pool at the axonal growth cones, as opposed to Tpm3.1, which lacks the two C-terminal amino acid residues. Our study provides further insight into the role of both Tpm3 products and the C-terminus of Tpm3.1, and it forms the basis for future studies that aim to identify the molecular mechanisms underlying Tpm3.1 targeting to different subcellular compartments.

scholarly journals Amino Acid Residues Gln4020and Lys4021of the Ryanodine Receptor Type 1 Are Required for Activation by 4-Chloro-m-cresol

2006 ◽  
Vol 281 (30) ◽  
pp. 21022-21031 ◽  
Author(s):  
James D. Fessenden ◽  
Wei Feng ◽  
Isaac N. Pessah ◽  
Paul D. Allen
Keyword(s):  
Amino Acid ◽  
Ryanodine Receptor ◽  
Receptor Type ◽  
Amino Acid Residues

scholarly journals Identification of Amino Acid Residues in the α, β, and γ Subunits of the Epithelial Sodium Channel (ENaC) Involved in Amiloride Block and Ion Permeation

1997 ◽  
Vol 109 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Laurent Schild ◽  
Estelle Schneeberger ◽  
Ivan Gautschi ◽  
Dmitri Firsov
Keyword(s):  
Amino Acid ◽  
Ion Selectivity ◽  
Site Directed Mutagenesis ◽  
Ion Permeation ◽  
Amino Acid Residues ◽  
Α Subunit ◽  
Na Ions ◽  
Membrane Spanning ◽  
A Site ◽  
Epithelial Sodium Channel Enac

The amiloride-sensitive epithelial Nachannel (ENaC) is a heteromultimeric channel made of three αβγ subunits. The structures involved in the ion permeation pathway have only been partially identified, and the respective contributions of each subunit in the formation of the conduction pore has not yet been established. Using a site-directed mutagenesis approach, we have identified in a short segment preceding the second membrane-spanning domain (the pre-M2 segment) amino acid residues involved in ion permeation and critical for channel block by amiloride. Cys substitutions of Gly residues in β and γ subunits at position βG525 and γG537 increased the apparent inhibitory constant (Ki) for amiloride by >1,000-fold and decreased channel unitary current without affecting ion selectivity. The corresponding mutation S583 to C in the α subunit increased amiloride Ki by 20-fold, without changing channel conducting properties. Coexpression of these mutated αβγ subunits resulted in a nonconducting channel expressed at the cell surface. Finally, these Cys substitutions increased channel affinity for block by externalZn2+ ions, in particular the αS583C mutant showing a Ki for Zn2+of 29 μM. Mutations of residues αW582L or βG522D also increased amiloride Ki, the later mutation generating a Ca2+blocking site located 15% within the membrane electric field. These experiments provide strong evidence that αβγ ENaCs are pore-forming subunits involved in ion permeation through the channel. The pre-M2 segment of αβγ subunits may form a pore loop structure at the extracellular face of the channel, where amiloride binds within the channel lumen. We propose that amiloride interacts with Na+ions at an external Na+binding site preventing ion permeation through the channel pore.

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