Burg D L, Furlong M T, Harrison M L, Geahlen R L
Department of Medicinal Chemistry and Pharmacognosy, Purdue University, West Lafayette, Indiana 47907.
J Biol Chem. 1994 Nov 11;269(45):28136-42.
Signaling through the B cell antigen receptor requires a complex set of interactions involving transmembrane components of the IgM receptor complex and cytosolic protein-tyrosine kinases. We have focused on the nature of these protein-protein interactions, the requirements for their occurrence, as well as the temporal sequence of events during the activation process. We found that cross-linking B cell antigen receptors at 0 degree C resulted in the rapid association of the Src-family protein-tyrosine kinase, Lyn, with the antigen receptor complex as judged by the presence of Lyn in anti-IgM and anti-phosphotyrosine immune complexes and the presence of MB-1 in anti-Lyn immune complexes. Receptor engagement also resulted in the rapid association of Lyn with the phosphotyrosine phosphatase, CD45. This association of Lyn with receptor components was stable in the detergent Brij 96, but was readily disrupted by Nonidet P-40, suggesting the involvement of hydrophobic interactions in stabilizing formation of the Lyn-receptor complex. The protein-tyrosine kinase, Syk, was also found associated with activated receptor complexes. This association of Syk with components of the antigen receptor complex was stable to Nonidet P-40. Antibodies directed against the carboxyl teminus of Syk, but not against the amino-terminal SH2 domain, co-immunoprecipitated MB-1 from activated cells, consistent with the binding of Syk through an SH2 domain-phosphotyrosine interaction.
通过B细胞抗原受体进行信号传导需要一系列复杂的相互作用，涉及IgM受体复合物的跨膜成分和胞质蛋白酪氨酸激酶。我们专注于这些蛋白质-蛋白质相互作用的性质、其发生的条件以及激活过程中事件的时间顺序。我们发现，在0摄氏度下交联B细胞抗原受体会导致Src家族蛋白酪氨酸激酶Lyn与抗原受体复合物迅速结合，这可通过抗IgM和抗磷酸酪氨酸免疫复合物中存在Lyn以及抗Lyn免疫复合物中存在MB-1来判断。受体结合还导致Lyn与磷酸酪氨酸磷酸酶CD45迅速结合。在去污剂Brij 96中，Lyn与受体成分的这种结合是稳定的，但很容易被Nonidet P-40破坏，这表明疏水相互作用参与了Lyn-受体复合物稳定形成的过程。还发现蛋白酪氨酸激酶Syk与活化的受体复合物相关联。Syk与抗原受体复合物成分的这种结合对Nonidet P-40是稳定的。针对Syk羧基末端而非氨基末端SH2结构域的抗体，从活化细胞中共免疫沉淀出MB-1，这与Syk通过SH2结构域-磷酸酪氨酸相互作用的结合一致。
