CALCIUM-BINDING SITES OF RABBIT TROPONIN AND CARP PARVALBUMIN
CALCIUM-BINDING SITES OF RABBIT TROPONIN AND CARP PARVALBUMIN
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DOI：
10.1016/0014-5793(75)80274-2
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发表时间：
1975-01-01
期刊：
影响因子：
3.5
通讯作者：
KAY, CM
中科院分区：
文献类型：
--
作者：
MILLER, TL;NELSON, DJ;KAY, CM
钙离子的瞬时流动调节肌肉收缩;脊椎动物肌肉含有肌钙蛋白，这是一种钙离子调节蛋白，被认为是通过与其他肌肉蛋白结合触发收缩的关键。肌钙蛋白由三种不同的多肽链组成，其中只有最轻的TN-C（mol. wt 17 846），结合多达四个Ca（II）[1]。兔肌TN-C [2]的氨基酸序列与小白蛋白mol. wt-11 500），一种来自鱼类和两栖动物白色肌肉的蛋白质，可结合两种Ca（II）[3]。Ca（II）的损失降低了两种蛋白质的螺旋含量[4-61]。鲤鱼小清蛋白的三维X射线结构已被确定[7，8]，但TN-C结构尚未解决。在小清蛋白的两个Ca（II）中，Ca（EF）在0.5 nm内被Phe-57的芳香族侧链覆盖。在用铽（III）取代Ca（II）并在259 nm处照射时，由于从Phe-57的芳族侧链到Tb（EF）的能量转移，出现了特征性的绿色Tb（III）发射[6，9]。Tb（III）发射也发生在TN-C中镧系元素离子取代Ca（II）后。然而，在这种蛋白质中，激发光谱鉴定出两个酪氨酰残基之一参与了向Tb（III）的能量转移[6]。在TN-C的氨基酸序列Tyr-109（108）与小白蛋白的Phe-57的比对中[2]，
Transient fluxes of calcium ion regulate muscle contraction; vertebrate muscle contain troponin, a calcium ion modulated protein believed to be critical in triggering contraction by its association with other muscle proteins. Troponin consists of three different polypeptide chains, only the lightest of which, TN-C (mol. wt 17 846), binds up to four Ca (II)[1]. The amino acid sequence of rabbit muscle TN-C [2] exhibits homologies with parvalbumin mol. wt-11 500), a protein from the white muscle of fish and amphibians that binds two Ca (II)[3]. Loss of Ca (II) reduces the helical content of both proteins [4-61. The three dimensional X-ray structure of a carp parvalbumin has been determined [7, 8], but the TN-C structure has not been solved. Of the two Ca (II) of parvalbumin, Ca (EF) is overlaid within 0.5 nm by the aromatic side chain of Phe-57. Upon substitution of Ca (II) by terbium (III) and irradiation at 259 nm a characteristic green Tb (III) emission appears, due-to energy transfer from the aromatic side chain of Phe-57 to Tb (EF)[6, 9]. Tb (III) emission also occurs upon substitution of the lanthanide ion for Ca (II) in TN-C. However, in this protein the excitation spectrum identifies one of the two tyrosyl residues as being involved in energy transfer to Tb (III)[6]. In the alignment of the amino acid sequences Tyr-109 (108) of TN-C matches with Phe-57 of parvalbumin [2], In this communication