Related Experiment Video
Updated: Jul 9, 2026

Quantitative Comparison of cis-Regulatory Element (CRE) Activities in Transgenic Drosophila melanogaster
Published on: December 19, 2011
CBP-independent activation of CREM and CREB by the LIM-only protein ACT
G M Fimia1, D De Cesare, P Sassone-Corsi
1Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS-INSERM-ULP, Illkirch, Strasbourg, France.
Abstract:
Transcriptional activation by CREB and CREM requires phosphorylation of a serine residue within the activation domain (Ser 133 in CREB; Ser 117 in CREM) which as a result interacts with the coactivator CBP. The activator CREM is highly expressed in male germ cells and is required for post-meiotic gene expression. Using a two-hybrid screen, we have isolated a testis-derived complementary DNA encoding a protein that we term ACT (for activator of CREM in testis), a LIM-only protein which specifically associates with CREM. ACT is expressed coordinately with CREM in a tissue- and developmentally regulated manner. It strongly stimulates CREM transcriptional activity in yeast and mammalian cells and contains an intrinsic activation function. As ACT bypasses the classical requirements for activation, namely phosphorylation of Ser 117 and interaction with CBP, it represents a new route for transcriptional activation by CREM and CREB. ACT may define a previously undiscovered class of tissue-specific coactivators whose function could be specific for distinct cellular differentiation programmes.
Related Concept Videos
RNA Polymerase II Accessory Proteins
Cell Specific Gene Expression
Co-activators and Co-repressors
Eukaryotic Transcription Activators
The binding domains are capable of recognizing and interacting with regulatory sequences on the DNA. These domains are...
Master Transcription Regulators
Co-activators and Co-repressors

