A structural model of human erythrocyte protein 4.1.
A structural model of human erythrocyte protein 4.1.
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DOI：
10.1016/s0021-9258(17)43089-4
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发表时间：
1984-04
期刊：
影响因子：
--
通讯作者：
T. Leto;V. Marchesi
中科院分区：
文献类型：
--
作者：
T. Leto;V. Marchesi
有限的蛋白质分解和特定的化学裂解方法使人们能够对人红细胞蛋白4.1进行详细的结构表征。这种蛋白质由两条化学上非常相似的多肽链(a和b)组成，表观分子质量分别为80,000和78,000道尔顿。蛋白质4.1在半胱氨酸残基上被2-硝基-5-硫氰基苯甲酸裂解，产生一系列不同约2,000道尔顿且具有相同的肽图的二联体。通过图谱分析对这些多肽进行比对，已将4个半胱氨酸残基定位于a和b多肽上17,000道尔顿片段中的4个半胱氨酸残基。在0摄氏度的温和胰凝乳酶处理主要在三个中心位置切割蛋白质4.1，并产生两个不相关的多肽家族。对这些片段在二维凝胶中的分析和通过肽图谱的分析揭示了蛋白质4.1结构中的一种不寻常的极性，因为每个多肽链包含两个片段，一个相对酸性，另一个相对碱性，它们在分子的相反两端分离。碱性区域被消化成一个富含半胱氨酸的30,000个道尔顿结构域，该结构域可以防止进一步的破坏，而酸性区域很容易被降解成更小的片段。来自酸性区域的多肽都以双重链的形式出现，表明蛋白4.1a和b多肽在酸性末端附近不同。在距离酸性末端约24,000-34,000道尔顿的一段内的两个多肽上存在相似的磷酸化位点。
Limited proteolysis and specific chemical cleavage methods have enabled a detailed structural characterization of human erythrocyte protein 4.1. This protein is composed of two chemically very similar polypeptide chains (a and b) with apparent molecular masses of 80,000 and 78,000 daltons. Cleavage of protein 4.1 at cysteine residues by 2-nitro-5-thiocyanobenzoic acid produces a series of doublets which differ by approximately 2,000 daltons and have identical peptide maps. Alignment of these peptides by mapping analysis has localized 4 cysteine residues within a 17,000-dalton segment on both a and b polypeptides. Mild chymotryptic treatment at 0 degrees C cleaves protein 4.1 primarily in three central locations and generates two families of unrelated peptides. Analysis of these fragments in two-dimensional gels and by peptide mapping reveals an unusual polarity in protein 4.1 structure in that each polypeptide chain contains two segments, one relatively acidic the other basic, that are segregated at opposite ends of the molecule. The basic region is digested into a cysteine-rich 30,000-dalton domain which resists further breakdown while the acidic region is readily degraded into smaller fragments. The peptides derived from the acidic region all appear as doublets suggesting that protein 4.1 a and b polypeptides differ close to the terminus of the acidic end. Similar phosphorylation sites occur on both polypeptides within a segment some 24,000-34,000 daltons from the acidic terminus.