Max H, Halder T, Kalbus M, Gnau V, Jung G, Kalbacher H
Medicine and Natural Sciences Research Center, University of Tübingen, Germany.
Hum Immunol. 1994 Sep;41(1):39-45. doi: 10.1016/0198-8859(94)90082-5.
The human Ca(2+)-binding (storage) protein calreticulin, located in the lumen of the endoplasmic reticulum, is proposed to play a role as autoantigen: anticalreticulin autoantibodies occur in the sera of patients with SLE and patients with onchocerciasis (calreticulin shows a high sequence homology to the Onchocerca volvulus antigen RAL-1). Here we present sequencing data of a HLA-DR4Dw4-associated calreticulin peptide fragment, Cal(295-310), purified from a DR4Dw4 self-peptide pool. Cal(295-310) proved to be one of three commonest self-peptides associated with DR4Dw4 molecules that were isolated from the EBV-transformed B-cell line BSM (DR4Dw4, DRw53). We tested the binding of Cal(295-309) and the analogous RAL-1 peptide to HLA-DR molecules: Cal(295-309) exhibited specific binding characteristics for DR4Dw4. Binding assays using self-peptide analogues with replaced amino acids led us to a DR4Dw4-binding motif with anchor residues at relative positions 1 and 6. The sequencing data suggest that calreticulin is a frequently processed intracellular protein. The abundance of calreticulin makes the presentation of different calreticulin peptides associated with HLA-D molecules likely to occur, supporting the immunologic relevance of this molecule.
人钙结合（储存）蛋白钙网蛋白位于内质网腔中，被认为可作为自身抗原发挥作用：抗钙网蛋白自身抗体存在于系统性红斑狼疮患者和盘尾丝虫病患者的血清中（钙网蛋白与盘尾丝虫抗原RAL-1具有高度序列同源性）。在此，我们展示了从DR4Dw4自身肽库中纯化出的与HLA-DR4Dw4相关的钙网蛋白肽片段Cal(295 - 310)的测序数据。Cal(295 - 310)被证明是从EB病毒转化的B细胞系BSM（DR4Dw4，DRw53）中分离出的与DR4Dw4分子相关的三种最常见自身肽之一。我们测试了Cal(295 - 309)和类似的RAL-1肽与HLA-DR分子的结合：Cal(295 - 309)对DR4Dw4表现出特异性结合特性。使用具有替换氨基酸的自身肽类似物进行的结合测定使我们得到了一个在相对位置1和6处具有锚定残基的DR4Dw4结合基序。测序数据表明钙网蛋白是一种经常被加工的细胞内蛋白。钙网蛋白的丰度使得与HLA-D分子相关的不同钙网蛋白肽的呈递很可能发生，这支持了该分子的免疫学相关性。
