FIG. 2.

Purification of CRG proteins and their function in an in vitro transcription assay. (A) The schematic shows the domains of the CRG (CREB-Gal4) proteins used, including the amino acids of CREB included in each. (B) CRG proteins were expressed in Sf9 insect cells using a baculovirus system. Proteins were purified from nuclear extracts using DNA affinity chromatography. Purified protein was separated on an SDS–15% PAGE gel and was silver stained by standard methods to visualize the protein bands. (C) Purified G4-DBD and CRG proteins were tested for activation in an in vitro transcription system with and without PKA added to the reaction as indicated.