Rühmann A, Bonk I, Köpke A K
Department of Molecular Neuroendocrinology, Max Planck Institute for Experimental Medicine, Göttingen, Germany.
Peptides. 1999 Nov;20(11):1311-9. doi: 10.1016/s0196-9781(99)00136-9.
The structure-activity relationship (SAR) between the recently identified neuropeptide urocortin (Ucn) and corticotropin-releasing factor (CRF) receptor, type 1 (CRFR1), has been investigated. To this end, rat Ucn (rUcn), ovine CRF (oCRF) and chimeric peptides of rUcn and oCRF were synthesized and tested for their binding affinity and potency to stimulate cAMP production in human embryonic kidney (HEK) 293 cells stably transfected with cDNA encoding rat CRFR1 (rCRFR1). In binding studies with [125I-TyrO]oCRF or [3H-Leu9]rUcn as radioligand, it was observed that rUcn but not oCRF bound in a similar fashion as the CRF antagonist astressin with high affinity to rCRFR1 coupled to G protein or uncoupled from G protein by guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). Consequently, rUcn was found to exert a significantly lower potency than oCRF to stimulate cAMP accumulation in transfected cells. CD spectroscopic investigations and reverse-phase HPLC (RPHPLC) retention behavior of the peptides suggested a more pronounced amphipatic alpha-helical character of rUcn when compared to oCRF and the chimeric peptides.
最近已对新发现的神经肽尿皮质素（Ucn）与促肾上腺皮质激素释放因子（CRF）受体1型（CRFR1）之间的构效关系（SAR）展开了研究。为此，合成了大鼠Ucn（rUcn）、绵羊CRF（oCRF）以及rUcn和oCRF的嵌合肽，并检测了它们对稳定转染了编码大鼠CRFR1（rCRFR1）的cDNA的人胚肾（HEK）293细胞中刺激cAMP产生的结合亲和力和效力。在用[125I-TyrO]oCRF或[3H-Leu9]rUcn作为放射性配体的结合研究中，观察到rUcn而非oCRF与CRF拮抗剂阿斯特辛以相似方式高亲和力地结合至与G蛋白偶联或通过鸟苷5'-O-（3-硫代三磷酸）（GTPγS）与G蛋白解偶联的rCRFR1。因此，发现rUcn在刺激转染细胞中cAMP积累方面的效力明显低于oCRF。肽的圆二色光谱研究和反相高效液相色谱（RPHPLC）保留行为表明，与oCRF和嵌合肽相比，rUcn具有更明显的两亲性α-螺旋特征。
