Mammalian ASIC2a and ASIC3 subunits co-assemble into heteromeric proton-gated channels sensitive to Gd3+
Mammalian ASIC2a and ASIC3 subunits co-assemble into heteromeric proton-gated channels sensitive to Gd3+
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DOI：
10.1074/jbc.m004114200
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发表时间：
2000-09-15
影响因子：
4.8
通讯作者：
Séguéla, P
中科院分区：
文献类型：
--
作者：
Babinski, K;Catarsi, S;Séguéla, P
酸敏感离子通道 (ASIC) 家族的质子受体在感觉神经元中表达，因此在有害性酸中毒的检测中发挥着关键作用。为了研究外周和中枢神经元中天然 ASIC 的亚基组成，我们将人类和啮齿动物 ASIC2a 和 ASIC3 亚基共同注射到非洲爪蟾卵母细胞中。共表达的 ASIC2a 和 ASIC3 亚基介导的酸诱导双相反应的幅度比各自同聚物介导的电流大得多（高达 20 倍），清楚地表明了功能关联。 ASIC2a+3电流的反转电位（大于或等于+20 mV）反映了主要对钠具有选择性的阳离子电流。单个与共表达的ASIC亚基对pH或阿米洛利的敏感性没有显着差异；然而，钆离子抑制 ASICS 和 ASIC2a+3 反应的效力（IC50 类似于 40 μM）比 ASIC2a 反应（IC50 大于或等于 1 mM）高得多。通过转染的人胚肾 (HEK293) 细胞和爪蟾卵母细胞的共纯化证明了 ASIC2a 和 ASIC3 亚基之间的生化相互作用。我们的原位杂交数据表明，大鼠 ASIC2a 和 ASIC3 转录本集中共定位，而逆转录聚合酶链反应数据使我们检测到人 ASIC2a 和 ASIC3 亚基在三叉神经感觉神经节、大脑和睾丸中的共表达，它们可能共同组装成对钆敏感的质子门控通道的新型亚型。
Proton receptors of the acid-sensing ion channel (ASIC) family are expressed in sensory neurons and thus could play a critical role in the detection of noxious acidosis. To investigate the subunit composition of native ASICs in peripheral and central neurons, we coinjected human as well as rodent ASIC2a and ASIC3 subunits in Xenopus oocytes, The amplitudes of acid-induced biphasic responses mediated by co-expressed ASIC2a and ASIC3 subunits were much larger (as much as 20-fold) than the currents mediated by the respective homomers, clearly indicating functional association. The reversal potential of the ASIC2a+3 current (greater than or equal to+20 mV) reflected a cationic current mainly selective for sodium, The sensitivity to pH or amiloride of single versus co-expressed ASIC subunits was not significantly different; however, gadolinium ions inhibited ASICS and ASIC2a+3 responses with much higher potency (IC50 similar to 40 mu M) than the ASIC2a response (IC50 greater than or equal to 1 mM). Biochemical interaction between ASIC2a and ASIC3 subunits was demonstrated by co-purification from transfected human embryonic kidney (HEK293) cells and Xenopus oocytes. Our in situ hybridization data showed that rat ASIC2a and ASIC3 transcripts are colocalized centrally, whereas reverse transcription-polymerase chain reaction data led us to detect co-expression of human ASIC2a and ASIC3 subunits in trigeminal sensory ganglia, brain, and testis where they might coassemble into a novel subtype of proton-gated channels sensitive to gadolinium.