PDZ proteins and polarity: functions from the fly.

Proteins that contain PDZ domains have been implicated in the localization of interacting partners to specific regions of the cell membrane. Although PDZ proteins that bind to a number of important mammalian proteins have been isolated, the significance of these interactions is unclear. In recent years, the fruit fly has emerged as a rich system for genetic analysis of PDZ protein function. Here, I discuss what the Drosophila data tell us about the roles and mechanisms of PDZ protein activity, and how this informs our understanding of PDZ function in other organisms.