Antibody Panel to CRE Binding Proteins

Introduction

The bZIP superfamily of eukaryotic DNA-binding transcription factors groups together proteins that contain a basic region mediating sequence - specific DNA-binding followed by a leucine zipper required for dimerization. bZIP domains usually bind a pallindromic 6 nucleotide site, but the specificity can be altered by interaction with accessory factor.

Several structure of bZIP have been solved. The basic region and the leucine zipper form a contiguous alpha helice where the four hydrophobic residues of the leucine zipper are oriented on one side. This conformation allows dimerization in parallel and it bends the helices so that the newly functional dimer forms a flexible fork where the basic domains, at the N-terminal open end, can then interact with DNA. The two leucine zipper are therefore oriented perpendicular to the DNA.

Within this quite large superfamily the mammalian cAMP response element (CRE) binding proteins form a subfamily. This family contains CREB, CREM, ATF1-7 and LRF1.

They are members of the Ser/Thr protein kinase super family and the cdc2/cdkx subfamily.

By definition, all Cdks share the feature that their enzymatic activation requires the binding of a cyclin regulatory subunit. In most cases, full activation also requires phosphorylation of a threonine near the kinase active site. Ckds are turned off by the binding of the CIP or INK4 proteins.

The cAMP response element (CRE) is an octanucleotide motif (TGACGTCA) that mediates diverse transcriptionally regulatory effects. It was first identified as an inducible enhancer of genes that can be transcribed in response to increased cAMP levels. Some growth control genes such as FOS have CRE in their transcriptional regulatory region and their expression is induced by increase in the intracellular cAMP levels. By cDNA cloning, multiple CRE-binding proteins have been identified. CREB1, originally called simply CREB, was isolated by Gonzalez et al. (1989); a gene called CREB2, or CREBP1, but officially designated ATF2 (activating transcription factor-2) was cloned by Maekawa et al. (1989). All of the CRE-binding proteins have the leucine zipper structure linked to a cluster of basic amino acids in their DNA-binding domain. The regulatory element TGACGTCA is found upstream of a number of viral and cellular genes. This element has been demonstrated to mediate cyclic AMP induction of cellular genes and activation of viral genes. The CREB or ATF proteins bind to this motif and mediate activation by cAMP and the adenovirus E1A protein. Activity of members of the CRE binding protein family is modulated by phosphorylation.

Antibody Tools for Detection of CRE Binding Proteins

Acris Antibodies offers a range of antibodies for detection of CRE Binding Proteins including CREB, phosphorylated CREB, and a full range of ATF antibodies (ATF1-7).

Picture Gallery

Fig.1: Detection of ATF-2 phosphorylation in HeLa cell lysate with anti-phospho ATF-2 mAb (Cat.no. SM7006P). Lane A. Untreated cell lysate; Lane B. HeLa cells treated with TNF for 1 hr.

Fig.2: Western blot analysis of ATF6 on 15 µg of (A) Jurkat and (B) NIH3T3 cell lysates using Cat.no. SM7007P. A protein band of approximately 90 kD was detected.

Fig. 3: Western blot analysis of CREB in HeLa cell lysate with anti-CREB mAb (Cat.no. SM7017P). A protein band of approximate molecular weight of 43 kDa was detected.

Fig 4: Confocal images of double immunostaining with phospho CREB (Ser133) antibody RA18008 (green) and calbindin (red) in the hippocampus using the sections from control and 24 hours reperfusion following 15 minute transient cerebral ischemia in rats. Yellow represents overlay of red and green.

Available Antibodies to CRE Binding Proteins / ATF

Anti- CREB1 (CREB), CREB2 (CREBP1, ATF2), CREB3 (LZIP), CREB3L1 (OASIS), CREB3L2 (BBF2H7),, CREB3L4 (CREB4, AIBZIP, JAL), CREB5, CREBL1 (ATF6-beta, Protein G13), CREBL2 , CREM (ICER), ATF1, ATF2 (CREB2), ATF3, ATF4, ATF5 (ATFX), ATF6 (ATF6-alpha), ATF7 (ATFA) antibody