In the cell, all RNAs are involved in interactions with proteins that influence many aspects of their processing, localization, and expression (reviewed inrefs.1 and 2 ). In order to gain mechanistic insights into the role of proteins in these processes, one must (1 ) define the sequence elements involved RNA processing and regulation of transcript function; (2 ) identify proteins that interact with these elements; and (3 ) create biochemical, molecular, and/or antibody reagents. Detailed insights into RNA-protein interactions are greatly facilitated by obtaining cDNA clones of the proteins of interest. In systems not amenable to genetic approaches, the isolation of cDNA clones is often preceded by the labor-intensive development of peptide sequence or antibody reagents. In this chapter, we describe a rapid Northwestern screening approach to identify cDNA clones for vertebrate RNA binding proteins that requires only prior knowledge of the RNA element.
