PTPN1
Tyrosine-protein phosphatase non-receptor type 1 also known as protein-tyrosine phosphatase 1B (PTP1B) is an enzyme that is the founding member of the protein tyrosine phosphatase (PTP) family. In humans it is encoded by the PTPN1 gene. PTP1B is a negative regulator of the insulin signaling pathway and is considered a promising potential therapeutic target, in particular for treatment of type 2 diabetes. It has also been implicated in the development of breast cancer and has been explored as a potential therapeutic target in that avenue as well.
Structure and function
PTP1B was first isolated from a human placental protein extract, but it is expressed in many tissues. PTP1B is localized to the cytoplasmic face of the endoplasmic reticulum. PTP1B can dephosphorylate the phosphotyrosine residues of the activated insulin receptor kinase. In mice, genetic ablation of PTPN1 results in enhanced insulin sensitivity. Several other tyrosine kinases, including epidermal growth factor receptor,insulin-like growth factor 1 receptor,colony stimulating factor 1 receptor,c-Src,Janus kinase 2,TYK2, and focal adhesion kinase as well as other tyrosine-phosphorylated proteins, including BCAR1,DOK1,beta-catenin and cortactin have also been described as PTP1B substrates.
