渗漏扫描
渗漏扫描(Leaky scanning)是真核生物細胞中核糖體(43S起始前複合物)掃描mRNA的5′非翻译区時,跳過前方的起始密碼子AUG,從較下游的AUG開始轉譯的機制。轉譯一般是由mRNA上最靠5'的AUG開始,但當其周圍序列配置不適合起始轉譯時,43S起始前複合物會跳過第一個AUG,繼續往3'掃描,改由較下游的AUG開始轉譯蛋白質[1][2]。
渗漏扫描的機制最早由美國生物學家玛丽莲·科扎克闡明。AUG密碼子在GCCRCCAUGG(Kozak序列,其中R表示A或G)中時最適合起始轉譯[3],當AUG周圍的序列與此不一致時,多數核糖體可能會發生滲漏掃描,即跳過該AUG,繼續往下游尋找更適宜起始轉譯的AUG,僅有少數核糖體會在該處起始轉譯,因此自可能轉譯生成數種不同的蛋白質[4]。渗漏扫描發生於許多病毒的mRNA轉譯過程[5],真核細胞自身的mRNA轉譯也有此機制[6][7]。
參考文獻
- ^ Kozak, Marilyn. Initiation of Translation in prokaryotes and eukaryotes. Gene. 1999, 234: 187-208. doi:10.1016/s0378-1119(99)00210-3.
- ^ Herzog, Etienne.; et al. Translation of the Second Gene of Peanut Clump Virus RNA 2 Occurs by Leaky Scanning In Vitro. Virology. 1995, 208: 215-225. doi:10.1006/viro.1995.1145.
- ^ Hinnebusch, Alan. Molecular Mechanism of Scanning and Start Codon Selection in Eukaryotes. American Society for Microbiology. 2011, 75 (3): 434-467. doi:10.1128/MMBR.00008-11.
- ^ Kozak, Marilyn. Pushing the limits of the scanning mechanism of initiation of translation. Gene. 2002, 299: 1-34. doi:10.1016/s0378-1119(02)01056-9.
- ^ Ryaboba, Lyubov.; et al. Translation reinitiation and leaky scanning in plant viruses. Virus Research. 2006, 119: 52-62. doi:10.1016/j.virusres.2005.10.017.
- ^ Zhou W, Song W. Leaky scanning and reinitiation regulate BACE1 gene expression.. Mol Cell Biol. 2006, 26 (9): 3353–64. PMC 1447409 . PMID 16611980. doi:10.1128/MCB.26.9.3353-3364.2006.
- ^ Kaur C, Kumar M, Patankar S. Messenger RNAs with large numbers of upstream open reading frames are translated via leaky scanning and reinitiation in the asexual stages of Plasmodium falciparum.. Parasitology. 2020, 147 (10): 1100–1113. PMID 32450933. doi:10.1017/S0031182020000840.