Isolation and characterization of the c-fos(rat) cDNA and analysis of post-translational modification in vitro.

c-fos mRNA accumulates to a level of 0.2% of cellular poly(A)-containing RNA 45 min after treatment of rat pheochromocytoma (PC12) cells with 1 mM barium chloride. Several clones of the c-fos(rat) cDNA were isolated from a cDNA library constructed from this RNA population. Nucleotide sequence analysis of a full-length cDNA clone reveals striking conservation among the c-fos genes isolated from rat, mouse and human cells, and confirms the c-fos gene structure predicted from an analysis of c-fos genomic clones. Translation of an SP6-derived transcript of the c-fos(rat) cDNA in a messenger-dependent rabbit reticulocyte lysate yields the complete c-fos protein. It undergoes extensive post-translational modification in the lysate, particularly in the presence of additional cAMP. The c-fos protein synthesized in vitro appears to be phosphorylated by the cAMP-dependent protein kinase.