DUF221 proteins are a family of osmosensitive calcium-permeable cation channels conserved across eukaryotes.
DUF221 proteins are a family of osmosensitive calcium-permeable cation channels conserved across eukaryotes.
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DUF221 蛋白是真核生物中保守的渗透敏感钙渗透性阳离子通道家族
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离子通过细胞膜通道的流动，特别是钙离子进入胞质溶胶，是真核生物环境反应的一个线索。在动物中，钙渗透性瞬时受体电位（TRP）通道可作为温度、渗透势和其他环境条件的传感器[1]。虽然植物也会对细胞溶质钙流的无数环境扰动做出反应[2]，但在陆地植物中没有发现动物中的应激门控钙渗透通道（如TRP）。几个蛋白质家族，包括谷氨酸受体样（GLR）蛋白、环核苷酸门控通道（CNGC）和膜联蛋白，已与植物细胞中的钙流相关[3]。然而，它们都没有被证明对压力信号有直接反应。由于胞质钙升高是植物细胞对胁迫处理的最早反应之一[1，4]，并且钙结合蛋白是几种环境胁迫反应所必需的[5]，因此胁迫激活的钙通道是可能将胁迫刺激与钙依赖性下游反应联系起来的候选者。因此，我们试图分离植物基因，编码可能的钙通道，门控的压力信号，如渗透stress.Using异源表达的拟南芥基因在中国卵巢（CHO）细胞加载的钙响应染料Fura-2，我们筛选未表征的完整的膜蛋白的钙敏感性钙电导。这些筛选导致拟南芥基因At 4G 22120的鉴定，其编码具有八个或更多个预测跨膜螺旋的整合膜蛋白。Fura-2荧光的比率监测表明，通过300 mM甘露醇处理施加的高渗休克处理诱导表达At 4G 22120（UniProt：Q5 XEZ 5）的CHO细胞中的钙升高，而含有空载体对照的细胞缺乏可辨别的钙升高（图1A）。所观察到的钙升高迅速发生，在高渗休克后数秒达到峰值，并且钙水平在1分钟内急剧下降
The flow of ions through channels in cell membranes, particularly the entry of calcium ions into the cytosol, serves as a cue for environmental responses in eukaryotes. In animals, calcium-permeable transient receptor potential (TRP) channels act as sensors for temperature, osmotic potential, and other environmental conditions [1]. Although plants also respond to myriad environmental perturbations with cytosolic calcium fluxes [2], stressgated calcium-permeable channels like TRPs in animals are not found in land plants. Several families of proteins, including glutamate receptor-like (GLR) proteins, cyclic nucleotide-gated channels (CNGCs), and annexins, have been linked to calcium fluxes in plant cells [3]. However, none of them has been shown to respond directly to stress signals. Because cytosolic calcium elevation is one of the earliest responses of plant cells to stress treatments [1, 4] and calcium-binding proteins are required for several environmental stress responses [5], stress-activated calcium channels are candidates that may link stress stimuli to calcium-dependent downstream responses. We thus seek to isolate plant genes that encode possible calcium channels that are gated by stress signals, such as osmotic stress.Using heterologous expression of Arabidopsis genes in Chinese Hamster Ovary (CHO) cells loaded with the calcium-responsive dye Fura-2, we screened uncharacterized integral membrane proteins for osmosensitive calcium conductance. These screens led to the identification of the Arabidopsis gene At4G22120, which encodes an integral membrane protein with eight or more predicted transmembrane helices. Ratiometric monitoring of Fura-2 fluorescence indicated that hyperosmotic shock treatment applied by 300 mM mannitol treatment induced calcium elevation in CHO cells expressing At4G22120 (UniProt: Q5XEZ5), whereas cells containing the empty vector control lacked discernible calcium elevation (Figure 1A). The observed calcium elevation occurred rapidly, peaking several seconds after hyperosmotic shock, and the calcium level sharply declined within 1 minute
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影响因子：
64.8
作者：
KNIGHT, MR;CAMPBELL, AK;TREWAVAS, AJ
通讯作者：
TREWAVAS, AJ
影响因子：
7.4
作者：
Swarbreck, Stephanie M.;Colaco, Renato;Davies, Julia M.
通讯作者：
Davies, Julia M.
影响因子：
7
作者：
Nühse, TS;Stensballe, A;Peck, SC
通讯作者：
Peck, SC
影响因子：
64.5
作者：
Schroeder BC;Cheng T;Jan YN;Jan LY
通讯作者：
Jan LY
影响因子：
7.2
作者：
Knight, H;Trewavas, AJ;Knight, MR
通讯作者：
Knight, MR