Cool D R, Loh Y P
Section on Cellular Neurobiology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Mol Cell Endocrinol. 1998 Apr 30;139(1-2):7-13. doi: 10.1016/s0303-7207(98)00081-1.
The binding of pro-opiomelanocortin,(POMC), pro-insulin, pro-enkephalin and chromogranin A (CGA) to the regulated secretory pathway sorting receptor, carboxypeptidase E (CPE), in bovine pituitary secretory granule (SG) membranes was investigated. N-POMC1-26, which contains the POMC sorting signal, bound to CPE in the SG membranes with low affinity and the binding was ion independent. Pro-insulin bound CPE with similar kinetics. Pro-enkephalin, but not CGA bound to CPE with similar IC50 as pro-insulin and N-POMC1-26. Crosslinking studies showed that pro-insulin and pro-enkephalin bound specifically to SG membrane CPE, similar to N-POMC1-26 reported previously. CPE was extracted from the SG membranes with NaHCO3 or KSCN, but not Triton X-100/1 M NaCl. The results show that CPE is tightly associated with SG membranes and binds several prohormones, but not CGA, with similar kinetics, providing further evidence that membrane CPE has the characteristics to function as a common sorting receptor for targeting prohormones to the regulated secretory pathway.
研究了阿片促黑皮质素原（POMC）、胰岛素原、脑啡肽原和嗜铬粒蛋白A（CGA）与牛垂体分泌颗粒（SG）膜中调节性分泌途径分选受体羧肽酶E（CPE）的结合情况。含有POMC分选信号的N-POMC1-26以低亲和力与SG膜中的CPE结合，且该结合不依赖离子。胰岛素原以类似的动力学与CPE结合。脑啡肽原而非CGA以与胰岛素原和N-POMC1-26类似的半数抑制浓度（IC50）与CPE结合。交联研究表明，胰岛素原和脑啡肽原与SG膜CPE特异性结合，类似于先前报道的N-POMC1-26。用碳酸氢钠或硫氰酸钾可从SG膜中提取CPE，但用吐温X-100/1 M氯化钠则不能。结果表明，CPE与SG膜紧密相关，并以类似的动力学结合几种激素原，但不结合CGA，这进一步证明膜CPE具有作为将激素原靶向调节性分泌途径的共同分选受体的特征。
