p62 (Phospho-Ser403) ELISA Kit

Sample

cell lysate

Species Reactivity

Human; Mouse

Intended Use

The Phospho-p62 Ser403 ELISA Kit is used for the semi-quantitative measurement of phosphorylated p62 proteins at serine 403 in human cell lysate or serine405 in mouse cell lysate.

Storage

- Upon receipt store all components at 4°C.
- Don't expose reagents to excessive light.

Sensitivity

The limit of detection (defined as such a concentration of phospho-p62 Ser403 giving absorbance higher than mean absorbance of blank* plus three standard deviations of the absorbance of blank: A blank + 3SD blank) is better than 0.73 AU/mL of sample.

General Description

The sequstosome1, p62/SQSTM1, hereafter referred as p62, is initially identified as a phosphotyrosine-independent ligand of the SH2 domain of p56lck. p62 is composed of multiple domain, which is Phox/Bem domain1, ZZ-type zinc finger domain, TRAF6 binding domain,
LC3-interacting region (LIR) motif, Keap1-interacting region (KIR), and ubiquitin-associated domain (UBA). Thus p62 plays a multifunctional scaffold protein that organizes signal transduction and protein traffic.
Additionally, binding to the autophagy regulator Atg8/LC3 through LIR motif and to the polyubiquitinated proteins through UBA domain, p62 is an important mediator for targeting polyubiquitinated proteins to the autophagic degradation system and p62 has a crucial role in the removal of aggregated proteins that are poorly degraded by proteasomes. The protein aggregates are characteristic features of a variety of chronic toxic and degenerative diseases, such as Mallory bodies in hepatocytes in alcoholic and non-alcoholic steatohepatitis, intracytoplasmic hyaline bodies in hepatocellular carcinoma, neurofibrillary tangles in neurons in Alzheimer's disease, Lewy bodies in Parkinson's disease, and Rosenthal fibers. Indeed, p62 is detected as a common component of these protein aggregates.
The phosphorylation of p62 modifies the affinity of domain for target protein. The phosphorylation of p62 on serine 403 (human) / serine 405 (mouse) in UBA domain, which is phosphorylated by casein kinase 2 and/or TANK-binding kinase 1, promotes its translocation to ubiquitinated proteins, and which progresses selective autophagic clearance of ubiquitinated proteins aggregates.
On the other hand, phosphorylation of p62 on serine 349 (human) / serine 351 (mouse) in KIR motif, which is phosphorylated by mTORC1 in vitro, enhances its affinity for Keap1, and which follows selective autophagy of Keap1, leading to Nrf2 activation. mTORC1 interacts with p62 via raptor and phosphorylates serine 349 (human) / serine 351 (mouse) of p62, which is required for mTORC1 activation in response to amino acids and is shown to be a nice marker of the activation of mTORC1 in autophagy pathways.