Lane W S, Galat A, Harding M W, Schreiber S L
Harvard Microchemistry Facility, Harvard University, Cambridge, Massachusetts 02138.
J Protein Chem. 1991 Apr;10(2):151-60. doi: 10.1007/BF01024778.
FKBP, an 11.8 kD intracellular protein that binds the immunosuppressants FK506 (Kd = 0.4 nM) and rapamycin (Kd = 0.2 nM) with high affinity, was purified to homogeneity from calf thymus. The complete amino acid sequence has been determined by automated Edman degradation of the intact molecule and overlapping fragments generated by proteolytic and chemical cleavage. The analysis revealed a 107 amino acid peptide chain with the following sequence: GVQVETISPGDGRTFPKRGQTCVVHYTGMLEDGKKFDSSRDRNKPFKFV- LGKQEVIRGWEEGVAQMSVGQRAKLTISPDYAYGATGHPGIIPPNATLIFDVELLKLE. The molecular weight, calculated from the amino acid sequence to be 11,778 D, was confirmed by electrospray ionization mass spectrometry. Thus, naturally isolated bovine FKBP does not appear to have any residues modified by glycosylation, phosphorylation, or other posttranslational derivatization processes. Bovine FKBP has only three amino acid residues that differ from human FKBP, whose sequence was elucidated by cloning and sequencing complementary DNA (Standaert et al., 1990). The protein has a substantial number of hydrophilic peptide segments with prevalent beta-strand type of chain fold. Understanding the biological function of FKBP and other members of the immunophilin class and their respective complexes with immunosuppressive drugs may provide insights into cytoplasmic signalling mechanisms, protein folding and translocation, and other cellular processes.
FKBP是一种11.8kD的细胞内蛋白质，它能以高亲和力结合免疫抑制剂FK506（解离常数Kd = 0.4 nM）和雷帕霉素（Kd = 0.2 nM），已从小牛胸腺中纯化至同质。完整的氨基酸序列已通过对完整分子以及由蛋白水解和化学裂解产生的重叠片段进行自动Edman降解来确定。分析揭示了一条107个氨基酸的肽链，其序列如下：GVQVETISPGDGRTFPKRGQTCVVHYTGMLEDGKKFDSSRDRNKPFKFV- LGKQEVIRGWEEGVAQMSVGQRAKLTISPDYAYGATGHPGIIPPNATLIFDVELLKLE。根据氨基酸序列计算出的分子量为11,778 D，通过电喷雾电离质谱法得到了证实。因此，天然分离的牛FKBP似乎没有任何经糖基化、磷酸化或其他翻译后衍生化过程修饰的残基。牛FKBP与人类FKBP只有三个氨基酸残基不同，人类FKBP的序列是通过克隆和测序互补DNA阐明的（斯坦达特等人，1990年）。该蛋白质有大量亲水性肽段，具有普遍的β链型链折叠。了解FKBP和免疫亲和素家族其他成员的生物学功能以及它们与免疫抑制药物各自形成的复合物，可能会为细胞质信号传导机制、蛋白质折叠和转运以及其他细胞过程提供深入见解。
