The seeds of silence

摘要

Individual microRNA sequences can suppress the production of hundreds of proteins. Reduction of protein levels in this way is often modest, however, and many such RNAs probably collectively fine-tune gene expression. MicroRNAs (miRNAs) are RNA sequences, roughly 23 nucleotides long, that are crucial regulators of gene expression. As part of an RNA-protein complex, these sequences form complementary base pairs with their target messenger RNA sequences, mediating mRNA degradation and/or repressing the translation of the mRNA into protein. Pertinent questions are which and how many proteins a specific miRNA affects, and how it does so. In this issue, Selbach et al. and Baek et al. address these questions through elegant, large-scale, quantitative studies of the effects of miRNAs on the human and mouse proteomes - the entire set of proteins expressed by the genome.