J. Biochem, 1988, Vol. 104, No. 3 457-460
© 1988 Japanese Biochemical Society
research-article |
Adenosine Binding Sites of Rat Pheochromocytoma PC 12 Cell Membranes: Partial Characterization and Solubilization1
Department of Biochemistry, Asahikawa Medical College Asahikawa, Hokkaido 078
3To whom correspondence should be addressed
Rat pheochromocytoma PC 12 cell membranes were shown to possess A2-like adenosine binding sites as assessed by using 5'-N-ethylcarboxamide[3H]adenosine ([3H]NECA). Specific [3H]NECA binding to PC 12 cell membrane at 0°C was saturable and showed a monophasic saturation profile. In contrast,[3H]NECA binding to PC 12 cell membrane at 30°C exhibited a biphasic profile suggesting the presence of two specific binding site. The rank order of potency for inhibition of [3H] binding at 0°C was NECA>2-chloroadenosine> 2',5'-dideoxyadenosine> isobutylmethylxanthine » phenylisopropyladenosine. These adenosine binding sites were solubilized with sodium cholate and the solubilized portion retained the same ligand binding characteristics as those of the membranebound form. Gel filtration experiments indicated an apparent Stokes radius of 6.7 nm for these adenosine binding sites/detergent complexes.
1This study was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan.
2Present address: Histopharmacology Section, Laboratory of Clinical Science, National Institutes of Mental Health, Building 10, Room 3D-48, Bethesda, Maryland 20892, U.S.A.