The ubiquitin-proteasome system (UPS) is an adenosine triphosphate (ATP)-dependent enzymatic machinery that targets substrate proteins for degradation by the 26S proteasome by tagging them with an isopeptide chain composed of covalently linked molecules of ubiquitin, a small chaperone protein. UPS is the main pathway of protein degradation in eukaryotic cells, and plays an important role in spermatogenesis. The dysfunction of various ubiquitin systems results in impaired sperm development with abnormal morphology and function, which is highly associated with male infertility. This review focuses on the roles of UPS in histone-to-protamine exchange, acrosome formation, sperm mitochondrial degradation and regulation of sperm function and quality.
Keywords: ubiquitin-proteasome system; acrosome formation; histone-to-protamine exchange; mitochondria; spermiogenesis.