ThepROX expression vector seriesareforexpressingproteinsin E.coli cell-free coupled transcription/translation systems, including PURESYSTEM®andThe RYTS Kit.Each vector in the seriescontains optimally positionedupstreamT7 promoter andRBS anddownstream T7 terminatorsequences.In addition, they encode N terminalProX (see below for explanation)and C terminalhexahistidinetags.Expression templates generated usingRYTS Linear Template Kitscontain convenient restriction enzyme sites to facilitate subcloningintopROX seriesexpression vectors.Used in conjunction with Protein Express'sCloverDirect™line of tRNA reagents for site-directed protein functionalization, pROX seriesexpression vectors can be used to expressproteins containing unnatural amino acids.CloverDirect™ UAGor CGGGaminoacyl tRNAs are available charged withdifferent unnatural amino acids that confer a range of functionality, including fluorescent-labeling, biotin-labeling,PEGylation, chemical crosslinking and photo-regulation. Targeting incorporationofspecific unnatural amino acids is achieved by designing proteinexpression templates with UAG and/or CGGG codons at user-defined positions.The ProX tag is a specialN terminal 14 residue peptidedesigned for the incorporation of certain large unnatural amino acids that require precise Nterminal positioning (codon 9) and a specific codon context (flanked by AAC and TCT).Codon 9 of the ProX tag can be varied betweenUAG, CGGG or TTT (as a control).