Reconciling the numbers: ESTs versus protein-coding genes

Abstract

The number of expressed sequences greatly surpasses the estimated number of protein-coding genes in mammalian genomes. An evolutionary approach reveals that only 9% to 14% of human-expressed and mouse-expressed sequences are able to code for proteins. Clustering of these sequences using cross-species relationships suggests that millions of expressed sequences may correspond to only approximately 20,000 distinct protein-coding transcripts.