Figure 1. Treatment of serum-starved HeLa cells with 20% FBS stimulates phosphorylation of eIF4E at Ser209, detected by the PathScan® Phospho-eIF4E (Ser209) Sandwich ELISA Kit #7938, but does not affect the levels of total eIF4E detected by PathScan® Total eIF4E Sandwich ELISA Kit #7940. HeLa cells (80-90% confluent) were serum-starved over night and then treated with 20% FBS at 37ºC. The absorbance readings at 450 nm are shown in the top figure, while the corresponding western blots using eIF4E Antibody #9742 (left panel) or Phospho-eIF4E Antibody (Ser209) #9741 (right panel) are shown in the bottom figure.
Figure 2. The relationship between the protein concentration of lysates from untreated and 20% FBS-treated HeLa cells and the absorbance at 450 nm using the PathScan® Phospho-eIF4E (Ser209) Sandwich ELISA Kit is shown.
|7938C||1 Kit (96 assays)||N/A|
|Product Includes||Volume||Solution Color|
|eIF4E Mouse mAb Coated Microwells||96 tests|
|Phospho-eIF4E (Ser209) Rabbit Detection mAb||1 ea||Green (Lyophilized)|
|Anti-rabbit IgG, HRP-linked Antibody (ELISA Formulated)||1 ea||Red (Lyophilized)|
|Detection Antibody Diluent||11 ml||Green|
|HRP Diluent||11 ml||Red|
|TMB Substrate 7004||11 ml|
|STOP Solution 7002||11 ml|
|Sealing Tape||2 ea|
|ELISA Wash Buffer (20X) 9801||25 ml|
|ELISA Sample Diluent||25 ml||Blue|
|Cell Lysis Buffer (10X) 9803||15 ml|
The PathScan® Phospho-eIF4E (Ser209) Sandwich ELISA Kit is a solid phase sandwich enzyme-linked immunosorbent assay (ELISA) that detects endogenous levels of eIF4E when phosphorylated at Ser209. An eIF4E mouse antibody has been coated onto the microwells. After incubation with cell lysates, eIF4E (phospho and nonphospho) is captured by the coated antibody. Following extensive washing, a Phospho-eIF4E (Ser209) rabbit detection antibody is added to the captured phospho and nonphospho eIF4E protein. Anti-rabbit IgG, HRP-linked Antibody #7074 is then used to recognize the bound detection antibody. HRP substrate, TMB, is added to develop color. The magnitude of the absorbance for this developed color is proportional to the quantity of phospho-eIF4E (Ser209).
Antibodies in kit are custom formulations specific to kit.
NOTE: Prepare solutions with purified water.
*NOTE: Some PathScan® ELISA Kits may include HRP-Linked Streptavidin in place of HRP-Linked Antibody.
NOTE: Initial color of positive reaction is blue, which changes to yellow upon addition of STOP Solution.
posted November 2013
Protocol Id: 204
CST's PathScan® Phospho-eIF4E (Ser209) Sandwich ELISA Kit #7938 detects endogenous levels of eIF4E protein when phosphorylated at Ser209. As shown in Figure 1, a significant induction of eIF4E phosphorylation at Ser209 can be detected in HeLa cells following treatment with 20% FBS using the Phospho-EIF4E (Ser209) Sandwich ELISA Kit. The levels of total eIF4E remain unchanged as shown by western analysis and by PathScan® Total eIF4E Sandwich ELISA Kit #7940 (Figure 1). This kit detects proteins from the indicated species, as determined through in-house testing, but may also detect homologous proteins from other species.
Eukaryotic initiation factor 4E (eIF4E) binds to the mRNA cap structure to mediate the initiation of translation (1,2). eIF4E interacts with eIF4G, a scaffold protein that promotes assembly of eIF4E and eIF4A into the eIF4F complex (2). eIF4B is thought to assist the eIF4F complex in translation initiation. Upon activation by mitogenic and/or stress stimuli mediated by Erk and p38 MAPK, Mnk1 phosphorylates eIF4E at Ser209 in vivo (3,4). Two Erk and p38 MAPK phosphorylation sites in mouse Mnk1 (Thr197 and Thr202) are essential for Mnk1 kinase activity (3). The carboxy-terminal region of eIF4G also contains serum-stimulated phosphorylation sites, including Ser1108, Ser1148, and Ser1192 (5). Phosphorylation at these sites is blocked by the PI3 kinase inhibitor LY294002 and by the FRAP/mTOR inhibitor rapamycin.
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