ATP-induced activation of expressed RyR3 at low free calcium.
Ca(2+) channel properties of the mink ryanodine receptor type 3 (RyR3), expressed in HEK293 cells, were studied in planar lipid bilayers to which RyR3 rich membrane fragments had been fused. RyR3 channels were not active at resting levels of Ca(2+)(free) but were gated by an additional 1 mM ATP, exhibiting long open times. The second major finding was the absence of channel inactivation at millimolar Ca(2+)(free). Insertion of a myc tag at the N-terminus of RyR3 did not affect the channel properties. As to skeletal muscle, the observed type 3 channel properties appear physiologically meaningful by assisting type 1 channels in calcium release.
Manunta
M
M
Institute for Biophysics, University of Linz, Altenberger Strasse 69, A-4040, Linz, Austria.
Rossi
D
D
Simeoni
I
I
Butelli
E
E
Romanin
C
C
Sorrentino
V
V
Schindler
H
H
D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002460:Cell Line; D004553:Electric Conductivity; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects*; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D008907:Mink; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D014162:Transfection
D008051:Lipid Bilayers; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D000255:Adenosine Triphosphate; D002118:Calcium