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Functional properties of the ryanodine receptor type 3 (RyR3) Ca 2+ release channel
Author(s) -
Sonnleitner Alois,
Conti Antonio,
Bertocchini Federica,
Schindler Hansgeorg,
Sorrentino Vincenzo
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.10.2790
Subject(s) - biology , ryanodine receptor , receptor , microbiology and biotechnology , biophysics , biochemistry
Single‐channel analysis of sarcoplasmic reticulum vesicles prepared from diaphragm muscle, which contains both RyR1 and RyR3 isoforms, revealed the presence of two functionally distinct ryanodine receptor calcium release channels. In addition to channels with properties typical of RyR1 channels, a second population of ryanodine‐sensitive channels with properties distinct from those of RyR1 channels was observed. The novel channels displayed close‐to‐zero open‐probability at nanomolar Ca 2+ concentrations in the presence of 1 mM ATP, but were shifted to the open conformation by increasing Ca 2+ to micromolar levels and were not inhibited at higher Ca 2+ concentrations. These novel channels were sensitive to the stimulatory effects of cyclic adenosine 5′‐diphosphoribose (cADPR). Detection of this second population of RyR channels in lipid bilayers was always associated with the presence of the RyR3 isoform in muscle preparations used for single‐channel measurements and was abrogated by the knockout of the RyR3 gene in mice. Based on the above, we associated the novel population of channels with the RyR3 isoform of Ca 2+ release channels. The functional properties of the RyR3 channels are in agreement with a potential qualitative contribution of this channel to Ca 2+ release in skeletal muscle and in other tissues.