c-FOS Antibody – Rabbit Monoclonal

The Fos gene family consists of 4 members: FOS, FOSB, FOSL1, and FOSL2. These genes encode leucine zipper proteins that can dimerize with proteins of the JUN family, thereby forming the transcription factor complex AP-1. As such, the FOS proteins have been implicated as regulators of cell proliferation, differentiation, and transformation. In some cases, expression of the FOS gene has also been associated with apoptotic cell death. [provided by RefSeq, Jul 2008]

Function: Nuclear phosphoprotein which forms a tight but non-covalently linked complex with the JUN/AP-1 transcription factor. In the heterodimer, FOS and JUN/AP-1 basic regions each seems to interact with symmetrical DNA half sites. On TGF-beta activation, forms a multimeric SMAD3/SMAD4/JUN/FOS complex at the AP1/SMAD-binding site to regulate TGF-beta-mediated signaling. Has a critical function in regulating the development of cells destined to form and maintain the skeleton. It is thought to have an important role in signal transduction, cell proliferation and differentiation. In growing cells, activates phospholipid synthesis, possibly by activating CDS1 and PI4K2A. This activity requires Tyr-dephosphorylation and association with the endoplasmic reticulum. Ref.9 Ref.10 Ref.12 Ref.15 Ref.17

Subunit structure: Heterodimer; with JUN

By similarity. Interacts with MAFB

By similarity. Component of the SMAD3/SMAD4/JUN/FOS complex required for syngernistic TGF-beta-mediated transcription at the AP1 promoter site. Interacts with SMAD3; the interaction is weak even on TGF-beta activation. Interacts with MAFB. Interacts with DSIPI; this interaction inhibits the binding of active AP1 to its target DNA. Interacts with CDS1 and PI4K2A

By similarity. Ref.6 Ref.10

Subcellular location: Nucleus. Endoplasmic reticulum. Cytoplasm › cytosol. Note: In quiescent cells, present in very small amounts in the cytosol. Following induction of cell growth, first localizes to the endoplasmic reticulum and only later to the nucleus. Localization at the endoplasmic reticulum requires dephosphorylation at Tyr-10 and Tyr-30. Ref.12 Ref.15 Ref.17

Developmental stage: Expressed at very low levels in quiescent cells. When cells are stimulated to re-enter growth, they undergo 2 waves of expression, the first one peaks 7.5 minutes following FBS induction. At this stage, the protein is localized endoplasmic reticulum. The second wave of expression occurs at about 20 minutes after induction and peaks at 1 hour. At this stage, the protein becomes nuclear. Ref.15

Post-translational modification: Phosphorylated in the C-terminal upon stimulation by nerve growth factor (NGF) and epidermal growth factor (EGF). Phosphorylated, in vitro, by MAPK and RSK1. Phosphorylation on both Ser-362 and Ser-374 by MAPK1/2 and RSK1/2 leads to protein stabilization with phosphorylation on Ser-374 being the major site for protein stabilization on NGF stimulation. Phosphorylation on Ser-362 and Ser-374 primes further phosphorylations on Thr-325 and Thr-331 through promoting docking of MAPK to the DEF domain. Phosphorylation on Thr-232, induced by HA-RAS, activates the transcriptional activity and antagonizes sumoylation. Phosphorylation on Ser-362 by RSK2 in osteoblasts contributes to osteoblast transformation

By similarity. Ref.9 Ref.11 Ref.15 Ref.17Constitutively sumoylated with SUMO1, SUMO2 and SUMO3. Desumoylated by SENP2. Sumoylation requires heterodimerization with JUN and is enhanced by mitogen stimulation. Sumoylation inhibits the AP-1 transcriptional activity and is, itself, inhibited by Ras-activated phosphorylation on Thr-232. Ref.12 Ref.14In quiescent cells, the small amount of FOS present is phosphorylated at Tyr-10 and Tyr-30 by SRC. This Tyr-phosphorylated form is cytosolic. In growing cells, dephosphorylated by PTPN2. Dephosphorylation leads to the association with endoplasmic reticulum membranes and activation of phospholipid synthesis. Ref.9 Ref.11 Ref.15 Ref.17

Sequence similarities: Belongs to the bZIP family. Fos subfamily.Contains 1 bZIP (basic-leucine zipper) domain.