代谢型谷氨酸受体2同源二聚体激活过程中单体选择机制的分析-生物化学与分子生物学专业论文.docx

华中科 技 大学 华 中 科 技 大 学 硕 士 学 位 论 文 II II Abstract Metabotropic glutamate receptors (mGluRs) belong to the Class C G-protein coupled receptors (GPCRs), which are constitutive dimer as the same as other members of the Class C. Different form GABABR and TIR, mGluRs are constitutive homodimer, and each monomer consists of Venus Flytrap Modual(VFT), Cystein rich Region(CRD), Heptahelical Domain(HD) and intracellular C-terminal. The research on cis-activation or trans-activation in homodimer activation and its activation mechanism are always hot topics. mGluRs are considered as model receptors in these researches for their stable dimerization and mutli-functional domains. We used mGluR2 as the study object, and detected cis-activation or trans-activation in the activation process of homodimer and domain participating in monomer selection mechanism. Firstly, we constructed artificial heterodimer of mGluR2 and functional missing mutants in VFT and i3loop through molecular biology methods. Transfected these plasmids into HEK293 cells through electroporation. Flex and IP3 function detection results showed that only trans-activation can be detected in mGluR2, different from both cis-activation and trans-activation exsiting in mGluR5. These indicated that there must be monomer selection mechanism in mGluR2 activation. Based on differences in mGluR5 and mGluR2 activation mechnism, we investigated CRD fuction in the monomer selection mechanism. The results showed that cis-activation can be detected in mGluR2 after replacing mGluR5-CRD into mGluR2-CRD, which needs futher confirmed. In summary, this research suggested that mGluR2 has only trans-activation and probably CRD affects on the choice of particular monomer in process of activation. These lay a foundation for research on the transduction of activation signal form VFTs-CRDs to HDs in mGluRs, even for the whole Class C GPCRs mechanism, meanwhile contributing to drug design and development targeted for the receptors. Key words: