Nonautonomous retrotransposons encode no protein • Alu elements contain the sequence AGCT that is recognized by the restriction enzyme Alu. I. They are present in up to a million copies in the human genome. • They can not transpose by themselves. Instead they take advantage of the retrotransposition machinery of other elements, such as LINEs.
Inducer: IPTG, lactose
Cut lactose and x-gal
重組蛋白質 在寄主(host)細胞中的表達 基因 優點 • 產量大 • 操作易 質體 染色體 4, 000 kb E. coli 缺點 • no post-translation modification • inclusion body • not secrete protein
重組蛋白質 在寄主細胞中的表達 E. coli 缺點 not secrete protein gram-positive bacteria B. subtilis proteases limited vector & promoter “signal” has not found yet