mhc主要组织相容复合物课件.ppt

1. 分子结构： (1) 肽结合区(a1/b1)：结合抗原肽 (2) Ig恒定区样结构(a2/b2)：与CD4结合 (3) 跨膜区：固定HLAII类抗原于膜上 (4) 胞浆区：信号转导 2. 组织分布: 专职APC、活化T细胞和胸腺上皮细胞 HLAII类抗原 概述 人类MHC-HLA复合体 HLA抗原系统 MHC的功能 HLA与医学的关系 主要内容 主 要 内 容 MHC的功能 一、抗原提呈 MHC分子的抗原结合凹槽选择性结合抗原肽 →形成抗原肽- MHC分子复合物 →以MHC限制性的方式供给T细胞识别 →启动特异性免疫应答。 Cell surface peptides of Ag Antigen recognition by T cells requires peptide antigens and presenting cells that express MHC molecules Y T T cell response No T cell response No T cell response No T cell response No T cell response Soluble native Ag Cell surface native Ag Soluble peptides of Ag Cell surface peptides of Ag presented by cells that express MHC antigens Antigen Presentation MHC class I accommodate accommodate peptides of 8-10 amino acids Cleft geometry MHC class II accommodate peptides of 13 amino acids b2-M a-chain Peptide a-chain b-chain Peptide Slices through MHC class I molecules, when viewed from above reveal deep, well conserved pockets Peptide binding pockets in MHC class I molecules Slices through MHC class II molecules, when viewed from above reveal shallow, poorly conserved pockets compared with those in MHC class I molecules Peptide binding pockets in MHC class II molecules MHC-binding peptides Each human usually expresses: 3 types of MHC class I (A, B, C) and 3 types of MHC class II (DR, DP,DQ) The number of different T cell antigen receptors is estimated to be 1,000,000,000,000,000 Each of which may potentially recognise a different peptide antigen How can 6 invariant molecules have the capacity to bind to 1,000,000,000,000,000 different peptides? Peptides can be eluted from MHC molecules Purify stable MHC-peptide complexes Fractionate and microsequence peptides Acid elute peptides 同一MHC分子提呈的不同抗原肽具有共同的基序 Eluted peptides from MHC molecules have different sequences but contain motifs Peptides bound to a particular type of MHC class I molecule have conserved patterns of amino acids P E I Y S F H I A V T Y K Q T L P S A