Grigoriadis D E, De Souza E B
Laboratory of Neurobiology, NIDA Addiction Research Center, Baltimore, MD 21224.
Peptides. 1989 Jan-Feb;10(1):179-88. doi: 10.1016/0196-9781(89)90095-8.
CRF receptors were characterized using radioligand binding and chemical affinity cross-linking techniques and localized using autoradiographic techniques in porcine, bovine and rat pituitaries. The binding of 125I-[Tyr0]-ovine CRF (125I-oCRF) to porcine anterior and neurointermediate lobe membranes was saturable and of high affinity with comparable KD values (200-600 pM) and receptor densities (100-200 fmoles/mg protein). The pharmacological rank order of potencies for various analogs and fragments of CRF in inhibiting 125I-oCRF binding in neurointermediate lobe was characteristic of the well-established CRF receptor in anterior pituitary. Furthermore, the binding of 125I-oCRF to both anterior and neurointermediate lobes of the pituitary was guanine nucleotide-sensitive. Affinity cross-linking studies revealed that the molecular weight of the CRF binding protein in rat intermediate lobe was identical to that in rat anterior lobe (Mr = 75,000). While the CRF binding protein in the anterior lobes of porcine and bovine pituitaries had identical molecular weights to CRF receptors in rat pituitary (Mr = 75,000), the molecular weight of the CRF binding protein in porcine and bovine intermediate lobe was slightly higher (Mr = 78,000). Pituitary autoradiograms from the three species showed specific binding sites for 125I-oCRF in anterior and intermediate lobes, with none being apparent in the posterior pituitary. The identification of CRF receptors in the intermediate lobe with comparable characteristics to those previously identified in the anterior pituitary substantiate further the physiological role of CRF in regulating intermediate lobe hormone secretion.
使用放射性配体结合和化学亲和交联技术对促肾上腺皮质激素释放因子（CRF）受体进行了表征，并运用放射自显影技术在猪、牛和大鼠的垂体中进行了定位。125I-[酪氨酸0]-羊CRF（125I-oCRF）与猪垂体前叶和神经中间叶膜的结合是可饱和的，且具有高亲和力，其解离常数（KD）值相当（200 - 600 pM），受体密度为（100 - 200 fmol/mg蛋白质）。各种CRF类似物和片段在抑制神经中间叶中125I-oCRF结合方面的药理效价排序，是垂体前叶中已确立的CRF受体的特征。此外，125I-oCRF与垂体前叶和神经中间叶的结合对鸟嘌呤核苷酸敏感。亲和交联研究表明，大鼠中间叶中CRF结合蛋白的分子量与大鼠前叶中的相同（Mr = 75,000）。虽然猪和牛垂体前叶中的CRF结合蛋白分子量与大鼠垂体中的CRF受体相同（Mr = 75,000），但猪和牛中间叶中CRF结合蛋白的分子量略高（Mr = 78,000）。来自这三个物种的垂体放射自显影片显示，125I-oCRF在前叶和中间叶有特异性结合位点，而在后叶中未观察到明显的结合位点。在中间叶中鉴定出具有与先前在垂体前叶中鉴定出的特征相当的CRF受体，进一步证实了CRF在调节中间叶激素分泌中的生理作用。
