CD45 function is regulated by an acidic 19-amino acid insert in domain II that serves as a binding and phosphoacceptor site for casein kinase 2
CD45 function is regulated by an acidic 19-amino acid insert in domain II that serves as a binding and phosphoacceptor site for casein kinase 2
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DOI：
10.4049/jimmunol.166.12.7208
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发表时间：
2001-06-15
影响因子：
4.4
通讯作者：
Justement, LB
中科院分区：
文献类型：
--
作者：
Greer, SF;Wang, YN;Justement, LB
在这项研究中，进行了实验，以阐明CD 45和酪蛋白激酶2（CK 2）之间的物理/功能关系。免疫沉淀实验表明，CK 2与CD 45相关，并且这种相互作用在B和T细胞系以及鼠胸腺细胞和脾B细胞中的Ag受体交联后是可诱导的。然而，酵母双杂交分析未能证明单个CK 2 α、α '或β亚基与CD 45之间的物理相互作用。相比之下，酵母三杂交测定，其中CK 2 α和β或α '和β亚基与CD 45的胞质结构域共表达，证明两种CK 2亚基都是与CD 45相互作用所必需的。使用酵母三杂交测定的实验还揭示了CD 45的结构域II中的19-aa酸性插入物介导CK 2和CD 45之间的物理相互作用。在CD 45缺陷型Jurkat细胞中表达野生型或突变型CD 45 RA和CD 45 RO同种型的结构/功能实验揭示了19-aa插入物对于最佳的CD 45功能是重要的。CD 45 RA和CD 45 RO重建CD 3介导的信号传导的能力的基础上测量的钙动员和丝裂原活化蛋白激酶的活化显着降低删除的19个氨基酸的插入。与缺失突变体相比，在19-aa插入丙氨酸内的四个丝氨酸残基的突变以类似的程度影响CD 45功能。这些研究结果支持了CD 45胞质结构域和CK 2之间的物理相互作用对CD 45的翻译后修饰很重要的假设，这反过来又调节其催化功能。
In this study experiments were conducted to elucidate the physical/functional relationship between CD45 and casein kinase 2 (CK2). Immunoprecipitation experiments demonstrated that CK2 associates with CD45 and that this interaction is inducible upon Ag receptor cross-linking in B and T cell lines as well as murine thymocytes and splenic B cells. However, yeast two-hybrid analysis failed to demonstrate a physical interaction between the individual CK2 alpha, alpha ', or beta subunits and CD45. In contrast, a yeast three-hybrid assay in which either CK2 alpha and beta or alpha ' and beta subunits were coexpressed with the cytoplasmic domain of CD45, demonstrated that both CK2 subunits are necessary for the interaction with CD45. Experiments using the yeast three-hybrid assay also revealed that a 19-aa acidic insert in domain II of CD45 mediates the physical interaction between CK2 and CD45. Structure/function experiments in which wild-type or mutant CD45RA and CD45RO isoforms were expressed in CD45-deficient Jurkat cells revealed that the 19-aa insert is important for optimal CD45 function. The ability of both CD45RA and CD45RO to reconstitute CD3-mediated signaling based on measurement of calcium mobilization and mitogen-activated protein kinase activation was significantly decreased by deletion of the 19-aa insert. Mutation of four serine residues within the 19-aa insert to alanine affected CD45 function to a similar extent compared with that of the deletion mutants. These findings support the hypothesis that a physical interaction between the CD45 cytoplasmic domain and CK2 is important for post-translational modification of CD45, which, in turn, regulates its catalytic function.