Protein - tyrosine phosphatase 1B (PTP1B) is a crucial enzyme belonging to the protein tyrosine phosphatase family. PTP1B is widely distributed in various tissues such as adipose, liver, muscle, and epithelial cells, mainly located in the endoplasmic reticulum of the cytoplasm. It specifically hydrolyzes the phosphate group on the phosphorylated tyrosine residue, maintaining the balance of tyrosine protein phosphorylation with protein tyrosine kinases and participating in cell signal transduction. PTP1B negatively regulates the insulin and leptin signaling pathways, and its over - expression is closely related to the occurrence of type 2 diabetes, obesity, and other diseases.