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Characterization of myocardial extracellular ATP receptors by photoaffinity labelling and functional assays
Author(s) -
Giannattasio Bartolo,
Powers Kit,
Scarpa Antonio
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80582-2
Subject(s) - labelling , receptor , extracellular , biochemistry , adenosine triphosphate , cytosol , photoaffinity labeling , affinity label , chemistry , biology , biophysics , enzyme
Extracellular ATP receptors in rat ventricular myocytes were investigated through intact cell photolabelling followed by protein isolation. 8‐Azido‐ATP (8Az‐ATP) was used for labelling under specific conditions determined by parallel functional studies. In those studies ATP‐induced cytosolic Ca 2+ transients were irreversibly and specifically inhibited by UV‐photolyzed 8Az‐ATP, but not by 2‐azido‐ATP (2Az‐ATP), even in the presence of high concentrations of phosphonucleotides not affecting myocardial ATP receptors. Under those conditions background labelling is minimized and radioactive 8Az‐ATP specifically labels a band of 45–48 kDa on a SDS gel. Labelling under the above conditions in the presence of ATPγS or 2‐methylthio‐ATP (2‐meSATP), which are distinct for two functionally different cardiac ATP receptors, shows two different proteins within the same band consistent with the possible labelling of these two receptors.