Peptidyl-prolyl isomerase (PPIase) Pin1 catalyzes cis/trans isomerization of the phospho- Serine/Threonine-Proline peptide bonds. Pin1 consists of short N-terminal protein-protein interaction domain that allows enzyme to bind phosphoproteins and longer C-terminal izomerase domain. Pin1 has many biological substrates, plays critical role in cell-cycle regulation, and up-regulated in many human cancers. Recently, Pin1 was linked to the Alzheimer’s disease pathogenesis. Pin1 can bind phosphorylated Thr-212/231 residues of Tau protein and increase its deposphorylation that may prevent formation of Tau neurofibrilary tangles.
The SensoLyte® Green Pin1 Assay Kit uses fluorogenic substrate that was pretreated to convert into cis isoform. Pin1 changes substrate into trans conformation that is readily cleaved to generate fluorescent signal which can be monitored at Ex/Em=490/520nm. Increase in fluorescence intensity is directly proportional to the Pin1 activity.