@article{GonzalesCaleroCuberoKlotz1992,
  author    = {Gonzales-Calero, G. and Cubero, A. and Klotz, Karl-Norbert},
  title     = {G protein coupled A\(_1\) adenosine receptors in coated vesicles of mammalian brain. Characterization by radioligand binding and photoaffinity labeling},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60435},
  year      = {1992},
  abstract  = {A\(_1\) adenosine receptors in coated vesicles have been characterized by radioligand binding and photoaflinity labelling. Saturation experiments with the antagonist 8-cyclopentyl-1 ,3-[\(^3\)H]dipropyl-xanthine ([\(^3\)H]DPCPX) gave a Kdvalue of 0.7 nM and a Bmax value of 82± 13 fmol/mg protein. For the highly A\(_1\)-selective agonist 2-chloro-N\(^6\)-[\(^3\)H]cyclopentyladenosine ([\(^3\)H]CCPA) a Kd value of 1.7 nM and a Bmax value of 72 ± 29 fmol/mg protein was estimated. Competition of agonists for [\(^3\)H]DPCPX binding gave a pharmacological profile with R-N\(^6\)-phenylisopropyladenosine (R-PIA) > CCPA > S-PIA > 5'-N-ethylcarboxamidoadenosine (NECA), which is identical to brain membranes. The competition curves were best fitted according to a two-site model, suggesting the existence of two affinity states. GTP shifted the competition curve for CCP A to the right and only one affinity state similar to the low affinity state in the absence of GTP was detected. The photoreactive agonist 2-azido-N\(^6\)- \(^{125}\)I-p-hydroxyphenylisopropyladenosine ([\(^{125}\)I]AHPIA) specifically labelled a single protein with an apparent molecular weight of 35,000 in coated vesicles, which is identical to A\(_1\) receptors labelled in brain membranes. Therefore, coated vesicles contain A\(_1\) adenosine receptors with similar binding characteristics as membrane-bound receptors, including GTP-sensitive high-affinity agonist binding. Photoaffinity labelling data suggest that A\(_1\) receptors in these vesicles are not a processed receptor fonn. These results confirm that A\(_1\) receptors in coated vesicles are coupled to a G-protein, and it appears that the A\(_1\) receptor systems in coated vesicles andin plasma membranes are identical.},
  subject      = {Toxikologie},
  language  = {en}
}
@article{ReddingtonKlotzLohseetal.1989,
  author    = {Reddington, M. and Klotz, Karl-Norbert and Lohse, M. J. and Hietel, B.},
  title     = {Radiation inactivation analysis of the A\(_1\) adenosine receptor: decrease in radiation inactivation size in the presence of guanine nucleotide},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60318},
  year      = {1989},
  abstract  = {Radiation inactivation analysis of the binding of the A1 adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine to rat brain membranes yielded a radiation inactivation size of 58 kDa. In the presence of GTPyS this was reduced to 33 kDa, in good agreement with the size of the ligand-binding subunit detected after photoaffinity labelling. The data indicate that the structural association of A\(_1\) adenosine receptors with G-protein components is altered in situ in the presence of guanine nucleotides.},
  subject      = {Toxikologie},
  language  = {en}
}