| Summary: | 碩士 === 國立陽明大學 === 微生物及免疫學研究所 === 93 === The Prp19-associated complex, which consists of at least eight proteins, binds to the spliceosome after U1 and U4 small nuclear ribonucleoprotein particles dissociate from the spliceosome during spliceosome activation. It plays roles in stabilizing U5 and U6 small nuclear ribonucleoprotein particles on the spliceosome by defining the specificity of their interaction with pre-mRNA. Syf1 is a component of the Prp19-associated complex, but its function in the complex or in spliceosome activation is unknown. The sequence of Syf1 was predicted to contain nine tetratricopeptide repeat motifs and may play a role in scaffolding. Here, I constructed a strain with SYF1 under the control of GAL1 promoter, and analyzed the function of a series of deletion mutants. It was demonstrated that the C-terminal half of Syf1 containing tetratricopeptide repeats 3 to 9 is sufficient for its essential function. The results of yeast two-hybrid analysis and in vivo depletion of Syf1 suggest that Syf1, particularly the tetratricopeptide repeats 3-to-9 region, is required for the integrity of the Prp19-associated complex. It was also confirmed that Ntc30 and Ntc20 play roles in modulating interactions of Syf1 with other components. From the results of antibody inhibition analysis, I proposed another possible role of Syf1 after the Prp19-associated complex binding to the spliceosome.
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