The pMAL™ Protein Fusion and Purification System (NEB# E8200) is available for producing a protein expressed from a cloned gene or open reading frame. The gene of interest is fused to the malE gene, which encodes maltose-binding protein (MBP), and expressed at levels constituting up to 40% of the total cell protein using the tac promoter and translation initiation signals of MBP. A one-step affinity purification for MBP is used to isolate the fusion protein. The IMPACT™ System (NEB# E6901) utilizes engineered protein splicing elements (inteins) to purify recombinant proteins by a single affinity column. This system distinguishes itself from other protein fusion systems by its ability to separate a recombinant protein from the affinity tag without the use of a protease. In addition, native recombinant proteins possessing a C-terminal thioester can be isolated for applications such as protein semisynthesis and site specific labeling. The K.lactis Protein Expression Kit (NEB# E1000) provides an easy method for expressing a gene of interest in the yeast Kluyveromyces lactis. Proteins may be produced intracellularly or be secreted using the supplied integrative expression vector pKLAC1. The PURExpress® In Vitro Protein Synthesis Kit (NEB# E6800 ) is a novel cell-free transcription/translation system reconstituted from the purified components necessary for E. coli translation.