Purified ryanodine receptor of skeletal muscle sarcoplasmic reticulum forms Ca2+-activated oligomeric Ca2+ channels in planar bilayers - PubMed (original) (raw)

Purified ryanodine receptor of skeletal muscle sarcoplasmic reticulum forms Ca2+-activated oligomeric Ca2+ channels in planar bilayers

L Hymel et al. Proc Natl Acad Sci U S A. 1988 Jan.

Abstract

The ryanodine receptor of sarcoplasmic reticulum (SR) from fast-twitch skeletal muscle has been purified and found by electron microscopy to be equivalent to the feet structures that are involved in situ in the junctional association of transverse tubules with terminal cisternae of SR. We now find that when the purified receptor is incorporated into vesicle-derived planar bilayers, it forms Ca2+-specific channels, which are dependent on submicromolar Ca2+ for activity. In the presence of 1 mM ATP, the channel shows essentially no activity at 10 nM Ca2+ but becomes highly activated at 50 nM Ca2+. At suboptimal Ca2+ levels (100 nM), the channel is strongly activated by 1 mM ATP and can be blocked by ruthenium red, both effects being prevented by higher Ca2+ levels (1 microM). Mg2+, added from the cis side at millimolar concentrations, blocks Ca2+ flux through the channel from trans to cis (equivalent to flux from luminal to myoplasmic compartment). Ryanodine stabilizes the open state of the channel and blocks the action of ruthenium red to close the channel. Thus, the purified ryanodine receptor incorporated into a bilayer has the Ca2+-channel characteristics consistent with the calcium release observed in isolated terminal cisternae vesicles. Furthermore, ryanodine induced the appearance of a sublevel gating mode characterized by long open conductance states, which were integral multiples of the smallest observed conductance, 3.8 pS in 50 mM Ca2+. The purified receptor consists essentially of a single-sized high molecular weight polypeptide (Mr. approximately equal to 360,000), which on reconstitution forms the square rectangles diagnostic of the feet structures. We conclude that the identity of the Ca2+-release channel of SR is the foot structure, which consists of an oligomer of the high molecular weight polypeptide.

PubMed Disclaimer

Cited by

Biophysical reviews top five: voltage-dependent charge movement in nerve and muscle.
Dulhunty AF. Dulhunty AF. Biophys Rev. 2023 Nov 10;15(6):1903-1907. doi: 10.1007/s12551-023-01165-3. eCollection 2023 Dec. Biophys Rev. 2023. PMID: 38192339 Review.
Image-Driven Modeling of Nanoscopic Cardiac Function: Where Have We Come From, and Where Are We Going?
Louch WE, Perdreau-Dahl H, Edwards AG. Louch WE, et al. Front Physiol. 2022 Mar 8;13:834211. doi: 10.3389/fphys.2022.834211. eCollection 2022. Front Physiol. 2022. PMID: 35356084 Free PMC article. Review.
Mechanisms and physiological implications of cooperative gating of clustered ion channels.
Dixon RE, Navedo MF, Binder MD, Santana LF. Dixon RE, et al. Physiol Rev. 2022 Jul 1;102(3):1159-1210. doi: 10.1152/physrev.00022.2021. Epub 2021 Dec 20. Physiol Rev. 2022. PMID: 34927454 Free PMC article. Review.
The Ryanodine Receptor as a Sensor for Intracellular Environments in Muscles.
Kobayashi T, Kurebayashi N, Murayama T. Kobayashi T, et al. Int J Mol Sci. 2021 Oct 6;22(19):10795. doi: 10.3390/ijms221910795. Int J Mol Sci. 2021. PMID: 34639137 Free PMC article. Review.
Regulation of the RyR channel gating by Ca2+ and Mg2.
Laver DR. Laver DR. Biophys Rev. 2018 Aug;10(4):1087-1095. doi: 10.1007/s12551-018-0433-4. Epub 2018 Jun 20. Biophys Rev. 2018. PMID: 29926426 Free PMC article. Review.

References

1. Biochemistry. 1986 Dec 16;25(25):8315-24 - PubMed
1. J Gen Physiol. 1986 Nov;88(5):573-88 - PubMed
1. J Biol Chem. 1987 May 15;262(14):6460-3 - PubMed
1. Nature. 1986 Sep 4-10;323(6083):66-8 - PubMed
1. FEBS Lett. 1980 Dec 15;122(1):77-9 - PubMed

Purified ryanodine receptor of skeletal muscle sarcoplasmic reticulum forms Ca2+-activated oligomeric Ca2+ channels in planar bilayers - PubMed (original) (raw)