The present invention provides compounds, compositions and methods for inhibiting D2R-DISC1 interaction. Specifically, the present invention provides a polypeptide comprising the amino acid sequence KIYIVLRRRRKRVNT (SEQ ID NO: 1) or SEQ ID NO:5, a fragment thereof, or a polypeptide comprising an amino acid sequence that is at least 80% identical to SEQ ID NO: 1 or 5, or a fragment thereof, wherein the polypeptide is not a naturally occurring dopamine receptor. Also provided is a method of identifying an agent that inhibits the interaction of D2R with DISC1, a method of identifying an agent that binds to the polypeptide sequence defined by SEQ ID NO: 1 or 5, and a method of inhibiting D2R interaction with DISC1 in a mammal comprising administering an agent that inhibits the interaction of D2R with DISC1 to the mammal.
