Abstract
Noncanonical proteins, encoded by previously overlooked genomic regions (part of the "dark genome"), are emerging as crucial players in human health and disease, expanding our understanding of the "dark proteome." This review explores their landscape, including proteins derived from long non-coding RNAs, circular RNAs, and alternative open reading frames. Recent advances in ribosome profiling, mass spectrometry, and proteogenomics have unveiled their involvement in critical cellular processes. We examine their roles in cancer, neurological disorders, cardiovascular diseases, and infectious diseases, highlighting their potential as novel biomarkers and therapeutic targets. The review addresses challenges in identifying and characterizing these proteins, particularly recently evolved ones, and discusses implications for drug discovery, including cancer immunotherapy and neoantigen sources. By synthesizing recent findings, we underscore the significance of noncanonical proteins in expanding our understanding of the human genome and proteome, and their promise in developing innovative diagnostic tools and targeted therapies. This overview aims to stimulate further research into this unexplored biological space, potentially revolutionizing approaches to disease treatment and personalized medicine.