Microproteins: Uncovering Hidden Layers of the Proteome.

Once dismissed as nonfunctional transcriptional noise, small open reading frames (sORFs) and their encoded microproteins have rapidly emerged as key players in diverse biological processes. Ranging from just a few to about 150 amino acids in length, microproteins are now recognized for their ability to modulate cellular functions, often acting as dominant-negative regulators, scaffolds, or signaling intermediates. Initially overlooked due to technical and conceptual limitations, they are increasingly being detected thanks to advances in high-resolution proteomics, ribosome profiling, and integrative bioinformatics. In this chapter, we provide a concise overview of the discovery, origins, functions, and biological significance of microproteins. We also introduce the structure of this methods book, which captures the latest experimental and computational tools used to identify, characterize, and functionally dissect microproteins across a wide range of organisms and research disciplines. This emerging field exemplifies the power of cross-disciplinary collaboration, and we hope this volume will support and inspire further research in this exciting and rapidly expanding area.