Role of calcium in serine transport into tobacco cells.
Role of calcium in serine transport into tobacco cells.
复制标题
钙在丝氨酸转运到烟草细胞中的作用。
DOI：
10.1104/pp.62.6.941
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发表时间：
1978
期刊：
影响因子：
7.4
通讯作者：
I. Smith
中科院分区：
文献类型：
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作者：
I. Smith
丝氨酸在烟草中的运输。Xanthi)细胞的液体培养条件进行了研究。丝氨酸转运在pH为4.0时最大。当细胞在含0.5 mM Ca(2+)的培养液中孵育时，观察到对转运的时间依赖性刺激。Ca(2+)预孵育6h后达到最大转运速率。Ca(2+)在丝氨酸转运中有三种不同的作用：依赖于时间的运输速率的刺激，维持高的运输速率，以及运输物质的滞留。钙(2+)或镁(2+)均有刺激作用，La(3+)或K(+)均有抑制作用。从转运介质中去除Ca(2+)会导致丝氨酸摄取速率的迅速下降。在去除Ca(2+)后加入La(3+)可以阻止这种下降。转移到缺钙培养基中的细胞失去了大量运输的丝氨酸，La(3+)或K(+)都能显著减少这种损失。在4小时内转运到细胞内的(45)Ca(2+)中，有75%可以与同一时期的介质Ca(2+)交换。丝氨酸向烟草细胞的运输涉及H(+)共转运，而Ca(2+)对烟草细胞的刺激是由于质子动力的增加。
The transport of serine into tobacco (Nicotiana tabacum L. var. Xanthi) cells grown in liquid medium was studied. Serine transport was maximal below pH 4.0. A time-dependent stimulation of transport was observed when cells were incubated in medium containing 0.5 mm Ca(2+). Maximum transport rates were achieved after 6 hours preincubation in Ca(2+). The following three distinct roles of Ca(2+) in serine transport were demonstrated: time-dependent stimulation of transport rate, maintenance of high transport rates, and retention of transported material. Stimulation occurred in the presence of either Ca(2+) or Mg(2+) and was inhibited by either La(3+) or K(+). Removal of Ca(2+) from the transport medium caused a rapid decline in the rate of serine uptake. This decline was prevented by addition of La(3+) after Ca(2+) removal. Cells transferred to medium lacking Ca(2+) lost substantial amounts of transported serine, this loss was significantly reduced by either La(3+) or K(+).Cells placed in (45)Ca(2+) rapidly bound more than 3 micromoles of Ca(2+)/gram fresh weight, which was exchangeable within 10 minutes with medium Ca(2+). Seventy-five per cent of the (45)Ca(2+) transported into the cells in 4 hours could be exchanged with medium Ca(2+) in the same period. The amount of net Ca(2+) transport into tobacco cells is insignificant relative to the total exchangeable Ca(2+).It is proposed that serine transport into tobacco cells involves H(+) cotransport and that the stimulation by Ca(2+) is due to an increase in the proton-motive force.