a ubiquitously expressed peripheral membrane protein that contains a PDZ domain and two coiled-coil regions. Associates with the Golgi apparatus and plasma membrane, regulating intracellular protein trafficking and degradation. May play a role in autophagy, and regulate the intracellular trafficking of the ADRB1 receptor. Interacts with GOLGA3 and STX6. The PDZ domain is known to mediate interactions with CLCN3-iso2, ACCN3, CFTR, SSTR5, FDZ5, ADRB1, FZD8, GRID2, mGluR5, mGluR1. Mutations of PDZ residues S302D, T304E, K348D, K350E abrogates the ability of PIST to interact with the CFTR C terminus. May regulate CFTR chloride currents and acid-induced ACCN3 currents by modulating cell surface expression of both channels. Overexpression results in CFTR intracellular retention and degradation in the lysosomes. Enriched in synaptosomal and postsynaptic densities (PSD) fractions. Expressed in cell bodies and dendrites of Purkinje cells. Localized at the trans-Golgi network (TGN) of spermatids and the medulla of round spermatides. An oncogenic fusion protein between PIST (aka FIG) and the receptor tyrosine kinase ROS is found in glioblastoma multiform. Unlike other fusion RTK oncogenes, he mechanism of activation of PIST-ROS does not appear to be dimerization. Rather, activation of the fused ROS kinase appears to depend upon translocation to the golgi apparatus: deletion of 2nd coiled-coil region, crucial for Golgi localization, appears to eliminate the transformation capacity of PIST-ROS. Three alternatively spliced human isoforms have been described. Note: This description may include information from UniProtKB.