González-Yanes C, Santos-Alvarez J, Sánchez-Margalet V
Departamento de Bioquímica Médica y Biología Molecular, Facultad de Medicina, Unidad de Investigación del Hospital Universitario Virgen Macarena, Av. Sánchez Pizjuan 4, Sevilla 41009, Spain.
Biochim Biophys Acta. 1999 Aug 12;1451(1):153-62. doi: 10.1016/s0167-4889(99)00084-1.
Pancreastatin (PST), a chromogranin A derived peptide with an array of effects in different tissues, has a role as a counterregulatory hormone of insulin action in hepatocytes and adipocytes, regulating glucose, lipid and protein metabolism. We have previously characterized PST receptors and signaling in rat hepatocytes, in which PST functions as a calcium-mobilizing hormone. In the present work we have studied PST receptors as well as the signal transduction pathways generated upon PST binding in adipocyte membranes. First, we have characterized PST receptors using radiolabeled PST as a ligand. Analysis of binding data indicated the existence of one class of binding sites, with a B(max) of 5 fmol/mg of protein and a K(d) of 1 nM. In addition, we have studied the G protein system that couples the PST receptor by gamma-(35)S-GTP binding studies. We have found that two G protein systems are involved, pertussis toxin-sensitive and -insensitive respectively. Specific anti-G protein alpha subtype sera were used to block the effect of pancreastatin receptor activation. Galpha(q/11) and to a lesser extent Galpha(i1,2) are activated by PST in rat adipocyte membranes. On the other hand, adenylate cyclase activity was not affected by PST. Finally, we have studied the specific phospholipase C isoform that is activated in response to PST. We have found that PST receptor is coupled to PLC-beta(3) via Galpha(q/11) activation in adipocyte membranes.
胰抑制素（PST）是一种源自嗜铬粒蛋白A的肽，在不同组织中具有一系列作用，它作为肝细胞和脂肪细胞中胰岛素作用的反调节激素，调节葡萄糖、脂质和蛋白质代谢。我们之前已对大鼠肝细胞中的PST受体和信号传导进行了表征，在这些细胞中PST作为一种钙动员激素发挥作用。在本研究中，我们研究了脂肪细胞膜中PST受体以及PST结合后产生的信号转导途径。首先，我们使用放射性标记的PST作为配体对PST受体进行了表征。结合数据分析表明存在一类结合位点，其B(max)为5 fmol/mg蛋白质，K(d)为1 nM。此外，我们通过γ-(35)S-GTP结合研究对与PST受体偶联的G蛋白系统进行了研究。我们发现涉及两个G蛋白系统，分别对百日咳毒素敏感和不敏感。使用特异性抗G蛋白α亚型血清来阻断胰抑制素受体激活的作用。在大鼠脂肪细胞膜中，Gα(q/11)以及程度较轻的Gα(i1,2)被PST激活。另一方面，腺苷酸环化酶活性不受PST影响。最后，我们研究了响应PST而被激活的特异性磷脂酶C同工型。我们发现，在脂肪细胞膜中，PST受体通过Gα(q/11)激活与PLC-β(3)偶联。
