Lorenzen A, Grün S, Vogt H, Schwabe U
Pharmakologisches Institut, Universität Heidelberg, Federal Republic of Germany.
Naunyn Schmiedebergs Arch Pharmacol. 1992 Jul;346(1):63-8. doi: 10.1007/BF00167572.
In solubilized extracts from bovine striatal membranes three different binding sites for 5'-N-ethylcarboxamidoadenosine ([3H]NECA) were observed after separation of the extract by gel filtration on Sepharose CL-6B. The first peak was eluted in the void volume and contained the A2 adenosine receptor. In the second peak, [3H]NECA binding sites were eluted with a pharmacological profile characteristic of adenotin, a low affinity non-receptor adenosine binding protein. The third peak represented approximately 50% of the [3H]NECA binding activity. This site bound [3H]NECA in a reversible and saturable manner with KD of 17 nmol/l and a binding capacity of 11.3 pmol/mg protein. In competition experiments, adenosine, NECA, NAD, inosine, 5'-AMP and S-adenosyl-L-homocysteine were the most potent ligands. In contrast to adenosine receptors, this site did neither bind adenosine receptor antagonists nor the A2 selective agonist CGS 21,680 (2-[p-(2-carboxyethyl)phenethylamino]5'-N-ethylcarboxamidoadeno sin e). These results suggest the existence of a novel high affinity binding site for adenosine of unknown function in bovine striatum.
在用琼脂糖凝胶CL-6B进行凝胶过滤分离牛纹状体膜的可溶提取物后，观察到5'-N-乙基甲酰胺基腺苷（[3H]NECA）有三个不同的结合位点。第一个峰在空体积中被洗脱，包含A2腺苷受体。在第二个峰中，[3H]NECA结合位点以腺嘌呤素的药理学特征被洗脱，腺嘌呤素是一种低亲和力非受体腺苷结合蛋白。第三个峰约占[3H]NECA结合活性的50%。该位点以可逆和饱和的方式结合[3H]NECA，KD为17 nmol/l，结合容量为11.3 pmol/mg蛋白质。在竞争实验中，腺苷、NECA、NAD、肌苷、5'-AMP和S-腺苷-L-高半胱氨酸是最有效的配体。与腺苷受体不同，该位点既不结合腺苷受体拮抗剂，也不结合A2选择性激动剂CGS 21,680（2-[对-(2-羧乙基)苯乙氨基]5'-N-乙基甲酰胺基腺苷）。这些结果表明，在牛纹状体中存在一种功能未知的新型腺苷高亲和力结合位点。
