Ca(2+)-induced Ca2+ release in myocytes from dyspedic mice lacking the type-1 ryanodine receptor.
While subtypes 1 and 2 of the ryanodine receptor (RyR) function as intracellular Ca2+ release channels, little is known about the function of the third subtype (RyR-3), first identified in brain. Myocytes from mice homozygous for a targeted mutation in the RyR-1 gene (dyspedic mice) can now be used for a study on the function of RyR-3, which is predominantly expressed in these cells according to our reverse transcription-polymerase chain reaction analysis. We here demonstrate in these myocytes caffeine-, ryanodine- and adenine nucleotide-sensitive Ca(2+)-induced Ca2+ release with approximately 10 times lower sensitivity to Ca2+ than that of RyR-1. Although RyR-3 does not mediate excitation-contraction coupling of the skeletal muscle type, we propose that RyR-3 may induce intracellular Ca2+ release in response to a Ca2+ rise with a high threshold.
Takeshima
H
H
Department of Neurochemistry, Tokyo Institute of Psychiatry, Japan.
Yamazawa
T
T
Ikemoto
T
T
Takekura
H
H
Nishi
M
M
Noda
T
T
Iino
M
M
D000227:Adenine Nucleotides / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002110:Caffeine / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D051379:Mice; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D009154:Mutation; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel
D000227:Adenine Nucleotides; D015220:Calcium Channels; D002148:Calmodulin-Binding Proteins; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D002110:Caffeine; D002118:Calcium