Residues distant from the active site influence protein-tyrosine phosphatase 1B inhibitor binding.

Regions of protein-tyrosine phosphatase (PTP) 1B that are distant from the active site yet affect inhibitor binding were identified by a novel library screen. This screen was based on the observation that expression of v-Src in yeast leads to lethality, which can be rescued by the coexpression of PTP1B. However, this rescue is lost when yeast are grown in the presence of PTP1B inhibitors.

Protein tyrosine phosphatase: enzymatic assays.

Activity assays for tyrosine phosphatases are based on the hydrolysis of a arylphosphate moiety from a synthetic substrate yielding a spectroscopically active product. Many different substrates can be used for these assays with p-nitrophenyl phosphate (pNPP), fluorescein diphosphate (FDP), and 6,8-difluoro-4-methylumbellyferyl phosphate (DiFMUP) being the most efficient and versatile. Equally, larger molecules such as phosphotyrosyl peptides can also be used to mimic more natural substrates.

Using yeast to screen for inhibitors of protein tyrosine phosphatase 1B.

Inhibition of protein tyrosine phosphatase 1B (PTP1B) has been proposed as a novel therapy to treat type 2 diabetes and obesity. In order to identify novel PTP1B inhibitors, we have developed a robust screen in Saccharomyces cerevisiae where growth is dependent on PTP1B catalytic activity. This was based on the observation that overexpression of v-Src, a tyrosine kinase, in yeast leads to lethality through mitotic dysfunction and this lethality can be reversed by co-expression of PTP1B.