Characterization of domains in C/EBP alpha that mediate its constitutive and cAMP-inducible activities

Structure/function analysis of CCAAT/enhancer binding proteins (C/EBP) alph a and beta have shown that they possess both constitutive and cAMP inducibl e activities. Three regions conserved between C/EBP alpha and beta were ide ntified which lie within the cAMP inducible domains of each protein. Deleti on analysis of these conserved regions within C/EBP alpha show that conserv ed region 2 plays a particularly critical role in mediating the PKA inducib le activity of the protein, however, the constitutive activity of conserved region 2 depends on promoter context. This data supports previous findings that constitutive and cAMP responsiveness arc mediated by domains of the p rotein that do not directly overlap, suggesting that they occur through dis tinct mechanisms. (C) 2001 Elsevier Science Ireland Ltd. All rights reserve d.