C-JUN

spinqualitylabelsall models Human C-Jun homodimer leucine zipper domain complex with acetyl (PDB code 1jun) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Introduction The c-Jun protein is a member of transcription factors which consist of a basic region leucine zipper region . Originally identified by its homology to v-jun, the oncogene from the avian sarcomoa virus . All these leucine zipper factors bind to DNA in one of two states: homo or heterodimers . In conjunction with the c-Fos protein these two proteins bind to specific regions of DNA strands. Together these two proteins form the c-fos/c-jun complex which help regulate cell growth and differentiation . The members of the jun and fos families include three Jun proteins and four Fos proteins (c-Jun, JunB, JunD,c-Fos, Fos-B, Fra1, and Fra2) . Regulation of the complex iteslf is done by interactions between the protein and DNA in addition to the protein-protein interactions between each of the leucine zipper domains . See Transcription and RNA Processing. Structure Overview The structure of c-Jun is comprised of a leucine zipper as previously stated. This dimerization motif may be in one of two classes, both of which are required for DNA-binding transcription factors; the basic-domain leucine zipper proteins (bZIP) and the basic helix loop-helix-leucine zipper proteins(bHLH-ZIP) . The strand becomes an elongated coiled coil. This is formed by residues at the a and d positions in each of the two monomers, whereby they create hydrophobic centers which conform to the "knobs into holes" model by Crick. . Amino acids at these a and d positions are each surrounded by 4 additional residues from adjacent a-helix monomer . The a and d residues each exhibit varying types of packing in terms of this "knobs into holes" theory. According to Harbury et al.(24) the leucines at the a positions are packed "parallel" in such a way that the C-alpha-C-beta bond vector lies in a parallel manner to the C-alpha-C-alpha vector at the base of the acceptor hole on adjacent helix . Whereas the opposite is true for the leucines in the d positions. Here the residues are packed in a "perpendicular" nature . The bond vector of the C-alpha-C-beta pack approximately perpendicular to the C-alpha-C-alpha vector at the base of the hole of the second helix in which it packs . Therefore only the leucine side chains in the a positions, which point away from the boundary, make van der Waals interactions . Protein Function The primary function of c-Jun is in regards to DNA transcription. Specifically, the protein is involved in proliferation, apoptosis, oncogenic transformation and various cellular processes . For instance cells which lack an allele for c-jun have been shown to stunt growth both in vitro and in vivo . Whereas a prolonged and therefore strong induction of c-jun has been in response to such things as tumor necrosis factor or stress inducing stimuli such as ultra violet radiation . Protein Regulation Changes made in the phosphorylation state of specific amino acids is one means by which c-Jun regulates transcription . To date two seperate sites of phosphorylation have been identified. One is located at the N-terminal end in which the amino acids Ser63 and Ser73 are phosphorylated in response to ras expression. When ras is expressed, and Ser63 and Ser73 are phosphorylated,and transcriptional activity of c-Jun increases. The second site is located at the C-terminal which is very close in proximity to the DNA binding domain. Here the residues are Thr214, Ser226, and Ser 232 . Unlike the two serines at the N-terminal end, phosphorylation at the C-terminal end inhibits DNA binding to c-Jun . Therefore with the expression of such oncogenes as ras dephsphorylation of these three residues occurs. Psychological Influences The stress-induced signaling cascade may also active c-Jun by phosphorylation. The N-ternminal protein kinase phosphorylates Ser63 and Ser73 . Another mechanism for the activation however is interestingly through intracellular calcium concentrations. Increasing these concentrations by opening the L-type voltage gated calcium channels leads to serines phosphorlation. It was found that the N-terminus contains both calcium and stress-regulated transcriptional activation domains . According to the study,distinct mechanisms of c-Jun control function by calcium and stress signals . Additional Resources To See Additional information, see: Transcription and RNA Processing

3D structure of C-JUN

Updated on 11-April-2018

Transcription and RNA Processing – hCJUN leucine zipper domain – human – NMR
Transcription and RNA Processing - hCJUN leucine zipper domain + DNA
1fos – hCJUN + p55 c-Fos + DNA
5fv8 – hCJUN + FOSW

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Andrew Rebeyka, Andrea Gorrell, Michal Harel, Alexander Berchansky, David Canner