Dynamics of Antarctic fish microtubules at low temperatures.
Dynamics of Antarctic fish microtubules at low temperatures.
复制标题
低温下南极鱼类微管的动态。
DOI：
10.1021/bi00438a028
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Detrich3rd,HW
中科院分区：
文献类型：
--
作者：
Himes,RH;Detrich3rd,HW
3月1日收到修订稿摘要：南极鱼类的微管蛋白从脑组织中纯化出来，去除了微管相关蛋白(MAP)，在体外高效地聚合，在近生理和超生理温度(5，10和20℃)下产生微管。通过使用标记的鸟苷5‘-三磷酸(GTP)作为微管蛋白二聚体的掺入、保留和丢失的标记物，研究了在这些温度下微管的动力学。微管质量在20℃达到稳定状态后，随着标记添加到微管溶液之前的间隔增加，在恒定持续时间的脉冲期间[~3H]GTP(即微管蛋白二聚体)的掺入速率逐渐减小到一个恒定的非零值。随着标记掺入速率的降低，微管的平均长度增加，微管的数量密度降低。因此，微管长度的重新分布(可能通过动态不稳定和/或微管退火)似乎是微管蛋白摄取率随时间下降的原因。当微管达到质量稳定状态和恒定长度分布时，标记的微管蛋白二聚体随时间的线性掺入速率分别为：5℃时的1.45 S“1，10℃时的0.48 S，20℃时的0.18 S‘1。因此，在较低的近生理温度下，微管表现出更高的亚单位通量或踏步速率。在每个温度下，在随后与过量的未标记GTP的追逐中，大部分结合的标记被微管保留。相反，当微管在5℃的[a-32P]GTP存在下重新组装，然后暴露在[~3H]GTP的脉冲中，在随后的与未标记的GTP的追逐中，32P标记随着时间的推移而丢失，而~3H标记被保留。综上所述，这些结果表明，南极鱼类的微管在低温下表现出与亚单位踏车和动态不稳定以及/或微管退火一致的行为。
Revised Manuscript Received March 1, 1989 abstract: The tubulins of Antarctic fishes, purified from brain tissue and depleted of microtubule-associated proteins (MAPs), polymerized efficiently in vitro to yield microtubules at near-physiological and supra-physiological temperatures (5, 10, and 20 C). The dynamics of the microtubules at these temperatures were examined through the use of labeled guanosine 5'-triphosphate (GTP) as a marker for the incorporation, retention, and loss of tubulin dimers. Following attainment of a steady state in microtubule mass at 20 C, the rate of incorporation of [3H] GTP (ie, tubulin dimers) during pulses of constant duration decreased asymptotically toward a constant, nonzero value as the intervalprior to label addition to the microtubule solution increased. Concomitant with the decreasing rate of label incorporation, the average length of the microtubules increased, and the number concentration of microtubules decreased. Thus, redistribution of microtubule lengths (probably via dynamic instability and/or microtubule annealing) appears to be responsible for the time-dependent decrease in the rate of tubulin uptake. When the microtubules had attained both a steady state in mass and a constant length distribution, linear incorporation of labeled tubulin dimers over time occurred at rates of 1.45 s" 1 at 5 C, 0.48 s" 1 at 10 C, and 0.18 s'1 at 20 C. Thus, the microtubules displayed greater rates of subunit flux, or treadmilling, at lower, near-physiological temperatures. At each temperature, most of the incorporated label was retained by the microtubules during a subsequent chase with excess unlabeled GTP. In contrast, when microtubules were assembled de novo in the presence of [a-32P] GTP at 5 C and then exposed to a pulse of [3H] GTP, the 32P label was lost over time during a subsequent chase with unlabeled GTP, whereas the 3H label was retained. Together, these results indicate that the microtubules of Antarctic fishes exhibit, at low temperatures, behaviors consistent both with subunit treadmilling and with dynamic instability and/or microtubule annealing.