2005 Fiscal Year Final Research Report Summary
The oxytocinase subfamily of M1 aminopeptidases
| Project/Area Number |
15390032
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biological pharmacy
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| Research Institution | RIKEN |
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Principal Investigator |
TSUJIMOTO Masafumi RIKEN, Lab.of Cell.Biochem., Chief Scientist, 辻本細胞生化学研究室, 主任研究員 (00281668)
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| Co-Investigator(Kenkyū-buntansha) |
HATTORI Akira RIKEN, Lab.of Cell.Biochem., Senior Research Scientist, 辻本細胞生化学研究室, 先任研究員 (50300893)
MASUDA Shinako RIKEN, Lab.of Cell.Biochem., Special Postdoctral Researcher, 辻本細胞生化学研究室, 基礎科学特別研究員 (30342851)
TANIOKA Toshihiro RIKEN, Lab.of Cell.Biochem., Special Postdoctral Researcher, 辻本細胞生化学研究室, 基礎科学特別研究員 (80360585)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Aminopeptidase / Oxytocinase Subfamily / Placental Leucine Aminopeptidase / Adipocyte-derived Leucine Aminopeptidase / Leukocyte-derived Arginine Aminopeptidase / NRK52E Cells / MHC Class I Antigenic Peptides / ER Retention Mechanism |
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| Research Abstract |
In our previous works, we identified and cloned two aminopeptidases (P-LAP and A-LAP) as novel enzymes belonging to the M1 family of aminopeptidases. In addition, we showed that A-LAP is a final processing enzyme of peptide antigens presented to MHC class I molecules in the endoplasmic reticulum (ER). Based on these results, we further examined the structural and functional analyses of M1 family members in this study and we identified one novel aminopeptidase. In addition, we have performed the functional analyses of these three enzymes that we have identified.
By searching a database, we have identified and cloned a novel protein designated as leukocyte-derived arginine aminopeptidase (L-RAP). Since L-RAP is homologous to P-LAP and A-LAP, we are now proposing that these three enzymes should be classified into "The oxytocinase subfamily of M1 aminopeptidases".
Functional analyses of P-LAP indicated that after treatment of renal-derived NRK52E cells with vasopressin, rapid translocation of P-LAP from intracellular vesicles to plasma membranes was observed. Since vasopressin is a good substrate of the enzyme, these results suggest the existence of the P-LAP-mediated negative feedback mechanism of vasopressin action in the kidney.
As for A-LAP, we have analyzed its ER-retention mechanism and found a protein binding to the enzyme. Since this protein contains an ER-retention signal (HDEL) in its C-terminal end, it is plausible that A-LAP is retained in the ER via binding to the protein. Based on this result, we will further examine the total aspect of the ER-retention mechanism of the enzyme.
It was also found that L-RAP is localized in the luminal side of the ER and can process N-extended precursor peptide antigens presented to the MHC class I molecules to mature forms. These results indicate for the first time that L-RAP is the second ER-aminopeptidase that can trim N-extended precursors to antigenic peptides.
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