Analysis of signal peptide-independent protein translocation into the endoplasmic reticulum

• Project/Area Number: 17K15089
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Functional biochemistry
• Research Institution: Shinshu University
• Principal Investigator: Hosomi Akira 信州大学, 学術研究院農学系, 助教 (60525864)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000); Fiscal Year 2017: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
• Keywords: タンパク質輸送 / シグナルペプチド / 酵母 / 分泌 / 小胞体

Outline of Final Research Achievements

The purpose of the study is clarification of mechanism of signal peptide-independent protein translocation into the endoplasmic reticulum in budding yeast. To clarify the mechanism, we tried to identify endogenous proteins that do not contain a conventional signal peptide but are still translocated into the ER in budding yeast. Through our analysis, we identified that a portion of a signal peptide-less, nuclear protein Rme1 can be translocated into the ER where is then undergoes N-glycosylation. The presence of Rme1 suggests that budding yeast contain a system for signal peptide-independent protein translocation into the ER.

Academic Significance and Societal Importance of the Research Achievements

真核生物の分泌は小胞体シグナペプチドが必要と考えられてきた。一方で、細胞質タンパク質が直接細胞外に出る経路が存在する。この経路は旧来の分泌経路を経ないので非古典的分泌と呼ばれている。近年のタンパク質の網羅的解析でシグナペプチドを持たないがN型糖鎖修飾されるタンパク質が非古典的分泌に分類されている。しかし、N型糖鎖修飾は小胞体内腔で起こるので、非古典的分泌には分類できない。したがって、シグナペプチド非依存的な小胞体へのタンパク質輸送は、これまでの輸送とは異なる新たなタンパク質輸送機構であると考えられる。