Exon-Specific RNA Interference: A Tool to Determine the Functional Relevance of Proteins Encoded by Alternatively Spliced mRNAs

The majority of metazoan genes encode pre-mRNAs that are subject to alternative splicing. For example, it has recently been estimated that as many as 74% of human genes encode alternatively spliced mRNAs (1 ). An alternatively spliced gene can generate anywhere from 2 different isoforms to as many as 38,016 isoforms in the case of the Drosophila Dscam gene (2 ). Thus, alternative splicing serves to greatly expand the diversity of the proteins encoded by a genome (3 ).