EFFECTS OF PEPTIDE LENGTH AND COMPOSITION ON BINDING TO AN EMPTY CLASS-I MHC HETERODIMER
EFFECTS OF PEPTIDE LENGTH AND COMPOSITION ON BINDING TO AN EMPTY CLASS-I MHC HETERODIMER
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DOI：
10.1021/bi00192a020
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发表时间：
1994-07-05
期刊：
影响因子：
2.9
通讯作者：
BJORKMAN, PJ
中科院分区：
文献类型：
--
作者：
FAHNESTOCK, ML;JOHNSON, JL;BJORKMAN, PJ
I类主要组织相容性复合体（MHC）蛋白在针对病毒的免疫应答期间将肽抗原呈递给T细胞。肽被装载到内质网中新合成的I类异二聚体中，使得大多数或所有细胞表面I类分子含有源自内源性或外源蛋白的肽。我们先前报道了鼠I类MHC分子H-2K（d）的空异源二聚体的组装，所述异源二聚体来自已去除内源性肽的变性重链和轻链[Fahnestock等（1992）Science 258，1658-1662]。在这里，我们测量空与肽填充分子的热稳定性曲线，并比较人与鼠轻链对Kd异源二聚体的整体稳定性的影响。大多数空的异二聚体在37 ℃下是稳定的，与轻链的种类无关，这表明我们先前关于出乎意料的高热稳定性的报道是K-d分子的固有性质，而不是由于使用了鼠/人嵌合蛋白。结合常数推导出一系列的肽与空的K-d异二聚体相互作用。四种已知的K-d限制性肽的解离常数范围为2.3 × 10 ~（-7）~ 3.4 × 10 ~（-8）M。使用一系列的24个类似肽，长度和肽的组成对一个K-d-限制性肽的结合亲和力的影响进行了探索，并解释了结果与参考已知的三维结构的I类MHC蛋白/肽复合物。
Class I major histocompatibility complex (MHC) proteins present peptide antigens to T cells during the immune response against viruses. Peptides are loaded into newly synthesized class I heterodimers in the endoplasmic reticulum such that most or all cell surface class I molecules contain peptides derived from endogenous or foreign proteins. We previously reported the assembly of empty heterodimers of the murine class I MHC molecule H-2K(d), from denatured heavy and light chains from which endogenous peptides had been removed [Fahnestock et al. (1992) Science 258, 1658-1662]. Here we measure thermal stability profiles of empty versus peptide-filled molecules and compare the effects of human versus murine light chains on the overall stability of the Kd heterodimer. The majority of empty heterodimers are stable at 37 degrees C regardless of the species of light chain, indicating that our previous report of the unexpectedly high thermal stability was an intrinsic property of the K-d molecule and not due to use of a murine/human chimeric protein. Binding constants are derived for a series of peptides interacting with empty K-d heterodimers. The dissociation constants of four known K-d-restricted peptides range from 2.3 X 10(-7) to 3.4 X 10(-8) M. Using a series of 24 analog peptides, the effects of length and peptide composition on binding affinity of one K-d-restricted peptide are explored, and the results are interpreted with reference to the known three-dimensional structures of class I MHC protein/peptide complexes.