Figure 1. Treatment of hSkMC or CHO (IR/IRS-1) cells with insulin stimulates phosphorylation of IRS-1 at Ser612, detected by the PathScan® Phospho-IRS-1 (Ser612) Sandwich ELISA Kit #7332, but does not affect the level of total IRS-1 protein detected by PathScan® Total IRS-1 Sandwich ELISA Kit #7328. hSkMC and CHO (IR/IRS-1) cells (80-90% confluent) were starved overnight and treated with 100 nM insulin for 7 minutes at 37oC. The absorbance readings at 450 nm are shown in the top figure, while the corresponding Western blots, using IRS-1 (L3D12) Mouse mAb #3194 (panels A & B) or Phospho-IRS-1 (Ser612) (L7B8) Mouse mAb #3193 (panels C & D), are shown in the bottom figure.
Figure 2. The relationship between the lysate protein concentration from untreated and insulin-treated CHO (IR/IRS-1) cells (A) or hSkMC cells (B) and the absorbance at 450 nm is shown.
Figure 3. Kit specificity as demonstrated by Western analysis of the ELISA microwell captured protein. Lysates were prepared from CHO (IR/IRS-1) cells and incubated in microwells coated with the IRS-1 capture antibody. Wells were washed, and the captured protein was solubilized in SDS gel loading buffer. Western analysis of CHO (IR/IRS-1) cell starting lysate (lanes 1 & 2) and the captured protein (lanes 3 & 4) was performed using IRS-1 (L3D12) Mouse mAb #3194. The major band detected in the captured material corresponds to IRS-1 (lanes 3 & 4).
|REACTIVITY||H M R|
|Product Includes||Volume||Solution Color|
|IRS-1 Rabbit mAb Coated Microwells||96 tests|
|IRS-1 Mouse Detection mAb||1 ea||Green (Lyophilized)|
|Anti-mouse 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® Total IRS-1 Sandwich ELISA Kit is a solid phase sandwich enzyme-linked immunosorbent assay (ELISA) that detects endogenous levels of IRS-1. An IRS-1 Rabbit Antibody has been coated onto the microwells. After incubation with cell lysates, IRS-1 (phospho and nonphospho) is captured by the coated antibody. Following extensive washing, IRS-1 Mouse Detection Antibody is added to detect the captured IRS-1 protein. Anti-mouse IgG, HRP-linked Antibody #7076 is then used to recognize the bound detection antibody. HRP substrate, TMB, is added to develop color. The magnitude of absorbance for this developed color is proportional to the quantity of total IRS-1.
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® Total IRS-1 Sandwich ELISA Kit #7328 detects endogenous levels of IRS-1. As shown in Figure 1, a significant induction of IRS-1 phosphorylation at Ser612 can be detected in hSkMC and CHO (IR/IRS-1) cells following treatment with insulin using the Phospho-IRS-1 (Ser612) Sandwich ELISA Kit #7332. However, the level of total IRS-1 (phospho and nonphospho) remains unchanged as shown by Western analysis and by PathScan® Total IRS-1 Sandwich ELISA Kit #7328 (Figure 1). In Figure 3, Western analysis of protein captured in microwells coated with the IRS-1 antibody shows a major band corresponding to the IRS-1 protein. This kit detects proteins from the indicated species, as determined through in-house testing, but may also detect homologous proteins from other species.
Human, Mouse, Rat
Insulin receptor substrate 1 (IRS-1) is one of the major substrates of the insulin receptor kinase (1). IRS-1 contains multiple tyrosine phosphorylation motifs that serve as docking sites for SH2-domain containing proteins that mediate the metabolic and growth-promoting functions of insulin (2-4). IRS-1 also contains over 30 potential serine/threonine phosphorylation sites. Ser307 of IRS-1 is phosphorylated by JNK (5) and IKK (6) while Ser789 is phosphorylated by SIK-2, a member of the AMPK family (7). The PKC and mTOR pathways mediate phosphorylation of IRS-1 at Ser612 and Ser636/639, respectively (8,9). Phosphorylation of IRS-1 at Ser1101 is mediated by PKCθ and results in an inhibition of insulin signaling in the cell, suggesting a potential mechanism for insulin resistance in some models of obesity (10).
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PathScan is a trademark of Cell Signaling Technology, Inc.