FIGURE 1.

Expression and purification of the full-length activators for the c-fos gene. A, schematic diagram of the c-fos gene. The regulatory cis-elements (SRE, FAP-1, and CRE) in the c-fos promoter and their cognate activators (SRF, Elk-1, CREB, and ATF1) are depicted in the diagram. B, purification schemes of SRF, Elk-1, CREB, and ATF1. Recombinant FLAG-tagged proteins were expressed in insect (High Five) cells, and their extracts were used for the following purification. Three columns (HiTrap heparin, HiTrap Q, and Mono S) were used for purification of SRF and Elk-1, whereas HiTrap SP and anti-FLAG M2 affinity resin were used for purification of CREB and ATF1. C, SDS-PAGE analysis of purified activators. Purified activators (∼1.0 μg) were resolved on a 10% SDS-polyacrylamide gel and stained with Coomassie Brilliant Blue.