Ruppelt A, Ma W, Borchardt K, Silberberg S D, Soto F
Max-Planck-Institut für experimentelle Medizin, Molekulare Biologie Neuronaler Signale, Göttingen, Germany.
J Neurochem. 2001 Jun;77(5):1256-65. doi: 10.1046/j.1471-4159.2001.00348.x.
We report here the cloning of a chicken cDNA (402 aa) showing high sequence similarity to the previously cloned rat and human P2X(5) receptors (67 and 69%, respectively). The chicken P2X(5) subunit is encoded by a gene composed of 12 translated exons, which shows conserved genomic structure with mammalian P2X genes. In HEK-293 cells heterologously expressing chicken P2X(5) receptors, ATP activates a current that desensitizes in a way that is dependent on the presence of extracellular divalent cations. ATP and 2-methylthio ATP are equipotent agonists (EC(50) approximately 2 microM) and suramin and pyridoxal 5-phosphate-6-azophenyl-2',4'-disulfonic acid are potent antagonists. Additionally, reversal potential measurements indicate that chicken P2X(5) is permeable not only to cations but also to chloride (P(Cs+)/P(Cl-) approximately 1.9), as has been described for native P2X receptor mediated responses in embryonic chicken skeletal muscle. mRNA distribution of chicken P2X(5) was determined by in situ hybridization analysis in both whole embryos and on tissue slices of heart and skeletal muscle. Our results suggest that chicken P2X(5) receptors are expressed in developing muscle and might play a role in early muscle differentiation.
我们在此报告一个鸡源cDNA（402个氨基酸）的克隆情况，该cDNA与先前克隆的大鼠和人类P2X(5)受体具有高度序列相似性（分别为67%和69%）。鸡P2X(5)亚基由一个包含12个编码外显子的基因编码，其基因组结构与哺乳动物的P2X基因具有保守性。在异源表达鸡P2X(5)受体的HEK - 293细胞中，ATP激活一种电流，该电流以依赖细胞外二价阳离子存在的方式脱敏。ATP和2 - 甲硫基ATP是等效激动剂（EC(50)约为2 microM），而苏拉明和5 - 磷酸吡哆醛 - 6 - 偶氮苯基 - 2',4' - 二磺酸是强效拮抗剂。此外，反转电位测量表明，鸡P2X(5)不仅对阳离子通透，对氯离子也通透（P(Cs+)/P(Cl-)约为1.9），这与胚胎期鸡骨骼肌中天然P2X受体介导的反应情况一致。通过对全胚胎以及心脏和骨骼肌组织切片进行原位杂交分析，确定了鸡P2X(5)的mRNA分布。我们的结果表明，鸡P2X(5)受体在发育中的肌肉中表达，可能在早期肌肉分化中发挥作用。
