The star family member QKI and cell signaling.

The family of Signal Transduction and Activators of RNA (STAR) is named based on the intriguing potential for these proteins to connect cell signaling directly to the homeostasis of their mRNA ligands. Besides the commonly shared single RNA binding domain that displays heterogeneous nuclear ribonucleoprotein K homology (KH), STAR proteins also harbor domains predicted to bind critical components in signal transduction pathways, in particular the Src-family protein tyrosine kinases (Src-PTK s). Indeed, accumulating evidence in recent years has demonstrated that the RNA-binding activity and the homeostasis of downstream mRNA targets of STAR proteins can be regulated by phosphorylation in response to various extracellular signals. This chapter provides a short review of the STAR member QKI, focusing on the essential role of QKI in development of the central nervous system, possible mechanisms by which QKI may link cell signaling to the cellular behavior of its mRNA targets and how QKI dysregulation may contribute to human diseases.