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. 2002 Jun 15;30(12):e59. doi: 10.1093/nar/gnf059

Figure 2.

Figure 2

Recombinant Cre proteins. The nlsCre protein contains the NLS of the SV40 large T antigen and the 9E10 c-myc epitope (myc-tag). TLM-nlsCre and PTD-nlsCre were generated by fusing the protein translocation sequences of the HBV PreS2 (6) or the HIV-1 Tat protein (7) to the N-terminus of Cre. Wild-type Cre protein (wtCre) was generated by removal of all C- and N-terminal heterologous sequences of nlsCre. (A) The composition of Cre variants following thrombin digestion. The N-terminal GS residues represent the P1′ and P2′ positions of the thrombin recognition site in the GST fusion proteins and are always present in the cleavage products. The only exchange in wtCre, which contains a serine residue at position 2, is therefore a glycine instead of a methionine residue at the first position. This is not expected to alter any property of the wild-type Cre recombinase. (B) Cre proteins were produced as GST fusion proteins in E.coli and affinity purified using glutathione–Sepharose. Elution of Cre proteins by thrombin cleavage resulted in highly enriched protein preparations of >80% purity. The eluates were separated by SDS–PAGE and proteins stained with Coomassie blue.