Molecular cloning, water channel activity and tissue specific expression of two isoforms of radish vacuolar aquaporin
Molecular cloning, water channel activity and tissue specific expression of two isoforms of radish vacuolar aquaporin
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DOI：
10.1093/oxfordjournals.pcp.a029453
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发表时间：
1998-09-01
影响因子：
4.9
通讯作者：
Maeshima, M
中科院分区：
文献类型：
--
作者：
Higuchi, T;Suga, S;Maeshima, M
研究了萝卜主根液泡中一种主要的膜内蛋白（VM 23）。VM 23的两种同种型，γ-和δ-VM 23的cDNA分别编码253和248个氨基酸的多肽，γ-和δ-VM 23对应于拟南芥的γ-和δ-TIP（液泡膜内在蛋白）。两种VM 23亚型的推导氨基酸序列有60%的相同性。γ-VM 23的氨基末端序列显示与纯化的VM 23的直接序列一致，表明γ-VM 23是VM 23同种型中最丰富的分子。当γ-和δ-VM 23的mRNA被注射到非洲爪蟾卵母细胞中时，卵母细胞的渗透水渗透性增加了6倍（60至200 μ m·s（-1））。这两种异构体的转录本在生长的下胚轴和幼叶中检测到高水平，但在幼苗根中未检测到delta-VM 23。光照促进了VM 23基因在子叶和根中的转录，但抑制了其在下胚轴中的表达，下胚轴的生长受到光的抑制。这些结果表明，VM 23的表达与细胞伸长密切相关。
A major membrane intrinsic protein (VM23) in vacuoles of radish (Raphanus) tap root was investigated. The cDNAs for two isoforms of VM23, gamma- and delta-VM23, encode polypeptides of 253 and 248 amino acids, respectively, gamma- and delta-VM23 correspond to the gamma- and delta-TIP (tonoplast intrinsic protein) of Arabidopsis. The deduced amino acid sequences of the two VM23 isoforms were 60% identical. The amino-terminal sequence of gamma-VM23 showed agreement with the direct sequence of the purified VM23, suggesting that gamma-VM23 is the most abundant molecule among the VM23 isoforms. When mRNAs of gamma- and delta-VM23 were injected into Xenopus oocytes, the osmotic water permeability of oocytes increased 6-fold (60 to 200 mu m s(-1)) of the control oocytes. The transcripts of both isoforms were detected in a high level in growing hypocotyls and young leaves, but delta-VM23 was not detected in seedling roots. Light illumination enhanced the transcription of two genes of VM23 in cotyledons and roots but suppressed their expression in hypocotyls the growth of which was inhibited by light. These findings suggest that the expression of VM23 is tightly related to cell elongation.