A human serotonin transporter mutation causes constitutive activation of transport activity
A human serotonin transporter mutation causes constitutive activation of transport activity
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DOI：
10.1124/mol.64.2.440
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发表时间：
2003-08-01
影响因子：
3.6
通讯作者：
Rudnick, G
中科院分区：
文献类型：
--
作者：
Kilic, F;Murphy, DL;Rudnick, G
在 HeLa 和 COS-7 细胞中测试了一种罕见的人类血清素转运蛋白 (hSERT) 变体的功能后果。该变体中 Ile-425 转化为 Val，其催化特性与野生型显着不同。在这两种细胞类型中，I425V 变体的血清素 (5-HT) 转运率较高。 V-max 的增加和 K-M 的减少都导致了速率的增加。 V-max 的增加并不是由转运蛋白表达的增加或转运蛋白在细胞表面和细胞内库之间的分布的增加来解释的。 K-M 的降低伴随着可卡因类似物 2β-甲甲氧基-3β-(4-[I-125]碘苯基)托烷结合的 K-D 的降低。在 HeLa 和 COS-7 细胞中，一氧化氮供体 S-亚硝基-N-乙酰青霉胺将野生型 hSERT 的活性提高到变体的活性，但没有改变 I425V 变体的活性。这种刺激被氧合血红蛋白（可猝灭一氧化氮）和鸟苷酸环化酶抑制剂的存在所阻止。
A rarely occurring variant of human serotonin transporter (hSERT) was tested for its functional consequences in HeLa and COS-7 cells. The variant, in which Ile-425 is converted to Val, was significantly different from wild type with respect to its catalytic properties. In both cell types, rates of serotonin (5-HT) transport were higher for the I425V variant. Both an increase in V-max and a decrease in K-M caused this increase in rate. The increase in V-max was not accounted for by increases in transporter expression or in the distribution of transporter between the cell surface and intracellular pools. The decrease in K-M was accompanied by a decrease in the K-D for binding of the cocaine analog 2beta-carbomethoxy-3beta- (4-[I-125] iodophenyl) tropane. In both HeLa and COS-7 cells, the nitric oxide donor S-nitroso-N-acetylpenicillamine increased the activity of wild-type hSERT to that of the variant but did not change the activity of the I425V variant. This stimulation was prevented by the presence of oxyhemoglobin, which quenches nitric oxide, and by an inhibitor of guanylyl cyclase.