2006 Fiscal Year Final Research Report Summary
Structural and functional analysis on protein complex of ubiquitin-proteasome system
| Project/Area Number |
15580308
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied molecular and cellular biology
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| Research Institution | Yokohama City University |
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Principal Investigator |
KAWASAKI Hiroshi Yokohama City University, International Graduate School of Arts and Sciences, Associate Professor, 国際総合科学研究科, 准教授 (70169704)
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| Co-Investigator(Kenkyū-buntansha) |
SASSA Hidenori Chiba university, Fucuity of Horticulture, Associate Professor, 園芸学部, 准教授 (50295507)
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| Project Period (FY) |
2003 – 2006
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| Keywords | Protein / Proteomics / Biotechnology / Proteasome / Ubiquitin / Protein complex / Posttranslational modification |
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| Research Abstract |
Protein degradation by ubiquitin-proteasome system is a major path of protein catabolism in cells. The ubiquitin-proteasome system regulates cell cycle, antigen presentation and plant self compatibility.
We have isolated proteasome and protein complex interacting proteasome subunits, and analyzed structure and functions. Four rice ATPase subunits of the proteasome were encoded by duplicated genes. We purified rice 19S complex of the proteasome and analyzed the expression of each gene products in various rice tissues. Tissue specific expression of each product suggests the preesence of multiform 19S complex engaged in the tissue-specific protein metabolism. The posttranslational modification of yeast 20S proteasome was analyzed. The phosphorylation sites of alpha7 subunit was determined. RPN4, originally identified as a subunit of 26S proteasome, is a transcriptional regulator for several subunits of proteasome. We isolated RPN4 complex from yeast cells by TAP method. Bud32 is reported to interact many subunits of proteasome. We isolated Bud32 complex from yeast haploid cells. The complex consisted of four proteins, Kael, Cgi121, Bud32 and Gon7. This complex was reported recently as KEOPS (for kinase, putative endopeptidase and other proteins of small size)/EKC (Endopeptidase-like Kinase Chromatin-associated), which regulates telomere maintenance or transcription of several genes. These proteins observed in nucleus and also in cytosol. The duploid deletion mutant of Bud32 shows random budding instead of bipolar budding pattern observed in normal cells. Budding pattern of deletion mutants on other members of the complex was not random. Bud32 complex isolated from duploid cells contained similar proteins. Some additional minor components were observed. These results suggest that Bud32 itself regulates budding pattern of duploid yeast cells.
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