This is a small, highly conserved protein with a single PDZ domain. PDZ (PSD-95/Discs large/ZO-1 homologous) domains promote protein-protein interactions that affect cell signaling, adhesion, protein scaffolding, and receptor and ion transporter functions. The encoded protein interacts with a large number of target proteins that play roles in signaling pathways; for example, it interacts with Rho A and glutaminase L and also acts as a negative regulator of the Wnt/beta-catenin signaling pathway. This protein was first identified as binding to the T-cell leukaemia virus (HTLV1) Tax oncoprotein. Overexpression of this gene has been implicated in altered cancer cell adhesion, migration and metastasis. The encoded protein also modulates the localization and density of inwardly rectifying potassium channel 2.3 (Kir2.3). To date, this protein has been shown to play a role in cell proliferation, development, stress response, and polarization.