Colás B, Arilla E, Prieto J C
Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá de Henares, Madrid, Spain.
J Recept Res. 1987;7(5):653-66. doi: 10.3109/10799898709056777.
Specific binding sites for somatostatin have been detected in cytosolic fraction of bovine cystic duct mucosa. At 37 degrees C, the interaction of 125I-Tyr11-somatostatin with cytosolic fraction was rapid, reversible, specific and saturable. At equilibrium, the binding of tracer was competitively inhibited by native peptide in the 1 nM to 2 microM range of concentrations. Scatchard analysis of binding data suggested the presence of two distinct classes of somatostatin binding sites: a class with a high affinity (Kd = 7.8 +/- 0.3 nM) and a low capacity (1.3 +/- 0.3 pmol somatostatin/mg protein) and a class with a low affinity (Kd = 129.1 +/- 2.0 nM) and a high capacity (43.5 +/- 6.7 pmol somatostatin/mg protein). The binding sites were shown to be highly specific for somatostatin since neuropeptides present in cystic duct such as Leu-enkephalin, neurotensin, substance P and vasoactive intestinal peptide did practically not show competition. These findings suggest that somatostatin could contribute to the regulation of the functions of the cystic duct mucosa in physiological and pathological conditions.
在牛胆囊管黏膜的胞质部分已检测到生长抑素的特异性结合位点。在37℃时，125I-Tyr11-生长抑素与胞质部分的相互作用迅速、可逆、特异且可饱和。在平衡状态下，浓度在1 nM至2 μM范围内的天然肽竞争性抑制示踪剂的结合。结合数据的Scatchard分析表明存在两类不同的生长抑素结合位点：一类具有高亲和力（Kd = 7.8 ± 0.3 nM）和低容量（1.3 ± 0.3 pmol生长抑素/毫克蛋白质），另一类具有低亲和力（Kd = 129.1 ± 2.0 nM）和高容量（43.5 ± 6.7 pmol生长抑素/毫克蛋白质）。由于胆囊管中存在的神经肽如亮脑啡肽、神经降压素、P物质和血管活性肠肽几乎不显示竞争作用，因此这些结合位点对生长抑素具有高度特异性。这些发现表明，生长抑素可能在生理和病理条件下有助于调节胆囊管黏膜的功能。
