poliproteiny

Poliproteiny, or polyproteins, are large protein precursors produced during the translation of certain messenger RNAs. A single polypeptide chain is synthesized and later cleaved by proteolytic enzymes into multiple mature proteins that often have distinct functions. This strategy allows coordinated production and processing of several proteins from one genetic transcript.

Poliproteiny are especially common in many positive-sense RNA viruses, where the viral genome is translated into one long polyprotein that is cleaved by viral proteases into structural and nonstructural proteins. Examples include poliovirus, dengue virus, West Nile virus and coronaviruses, such as SARS-CoV-2, which generate a single large polyprotein that is chopped into functional units by viral proteases like 3C-like protease and others. Some cellular proteins and certain multi-domain organisms also employ polyprotein strategies, though this is rarer outside viral systems.

The cleavage of polyproteins is tightly regulated in time and location, often occurring co-translationally or soon after translation. Specific protease recognition sites determine where processing occurs, shaping the final composition and stoichiometry of mature proteins. This mode of expression economizes the genome and enables rapid, coordinated production of multiple components that must act together.

In research and therapeutics, polyprotein concepts aid in understanding viral replication and in designing antiviral strategies that inhibit proteases responsible for polyprotein processing. Distinguishing polyproteins from polypeptides is crucial: polypeptides are typically single-function chains, while polyproteins must be processed to yield multiple functional products.