CREB-TF (CREB, cAMP response element-binding protein) is a cellular transcription factor. It binds to certain DNA sequences called cAMP response elements (CRE), thereby increasing or decreasing the transcription of the genes. CREB was first described in 1987 as a cAMP-responsive transcription factor regulating the somatostatin gene.

Genes whose transcription is regulated by CREB include: c-fos, BDNF, tyrosine hydroxylase, numerous neuropeptides (such as somatostatin, enkephalin, VGF, corticotropin-releasing hormone), and genes involved in the mammalian circadian clock (PER1, PER2).

CREB is closely related in structure and function to CREM (cAMP response element modulator) and ATF-1 (activating transcription factor-1) proteins. CREB proteins are expressed in many animals, including humans.

CREB has a well-documented role in neuronal plasticity and long-term memory formation in the brain and has been shown to be integral in the formation of spatial memory. CREB downregulation is implicated in the pathology of Alzheimer's disease and increasing the expression of CREB is being considered as a possible therapeutic target for Alzheimer's disease. CREB also has a role in photoentrainment in mammals.

The following genes encode CREB or CREB-like proteins:

CREB proteins are activated by phosphorylation from various kinases, including PKA, and Ca²⁺/calmodulin-dependent protein kinases on the Serine 133 residue. When activated, CREB protein recruits other transcriptional coactivators to bind to CRE promoter 5’ upstream region. Hydrophobic leucine amino acids are located along the inner edge of the alpha helix. These leucine residues tightly bind to leucine residues of another CREB protein forming a dimer. This chain of leucine residues forms the leucine zipper motif. The protein also has a magnesium ion that facilitates binding to DNA.

The cAMP response element (CRE) is the response element for CREB which contains the highly conserved nucleotide sequence, 5'-TGACGTCA-3’. CRE sites are typically found upstream of genes, within the promoter or enhancer regions. There are approximately 750,000 palindromic and half-site CREs in the human genome. However, the majority of these sites remain unbound due to cytosine methylation, which physically obstructs protein binding.

A generalized sequence of events is summarized as follows: A signal arrives at the cell surface, activates the corresponding receptor, which leads to the production of a second messenger such as cAMP or Ca²⁺, which in turn activates a protein kinase. This protein kinase translocates to the cell nucleus, where it activates a CREB protein. The activated CREB protein then binds to a CRE region, and is then bound to by CBP (CREB-binding protein), which coactivates it, allowing it to switch certain genes on or off. The DNA binding of CREB is mediated via its basic leucine zipper domain (bZIP domain) as depicted in the image. Evidence suggests the β-adrenoceptor (a G-protein coupled receptor) stimulates CREB signalling.