Furin-mediated protein processing in infectious diseases and cancer

Braun, Elisabeth; Sauter, Daniel

To date, furin-mediated cleavage has been described for envelope glycoproteins encoded by numerous evolutionarily diverse virus families, including Herpes-, Corona-, Flavi-, Toga-, Borna-, Bunya-, Filo-, Orthomyxo-, Paramyxo-, Pneumoand Retroviridae (Table 2) . Although viral furin substrates generally harbour the canonical polybasic cleavage site, timing and subcellular localisation of furin-mediated activation may differ substantially between virus families. Since furin and viral glycoproteins both enter the secretory pathway, proteolytic activation can occur at different steps of the viral replication cycle. While the envelope proteins of some viruses are cleaved in the producer cell, others are processed in the extracellular space or during entry into their target cells (Figure 3 ). The following sections highlight the characteristics of a few selected viral glycoproteins, their processing by furin and the importance of furin-mediated cleavage for infection and pathogenicity.