Transmembrane protein 88 (TMEM88) is a two-transmembrane-type protein whose C-terminal tail has been shown to bind the PDZ domain of Dishevelled (Dvl), one of the key components in Wnt signaling pathways. TMEM88 attentuated the Wnt/beta-catenin signaling induced by Wnt-1 ligand in a dose-dependent manner and knockdown of TMEM88 by RNAi increased Wnt activity, suggesting that TMEM88 plays a role in regulating Wnt signaling in a context-dependent manner.