Post-translational cleavage

Protease is responsible for cleaving these precursor molecules to produce the final structural proteins of the mature virion core. By preventing post-translational cleavage of the Gag-Pol polyprotein, protease inhibitors (Pis) prevent the processing of viral proteins into functional conformations, resulting in the production of immature, noninfectious viral particles (Figure 49-4). Protease inhibitors are active against both HIV-1 and HIV-2 unlike the NRTTs, however, they do not need intracellular activation. 

In eukaryotes, each mRNA is monocistronic, that is, discounting any subsequent post-translational cleavage reactions that may occur, the mRNA encodes a single protein. In prokaryotes, many mRNAs are polycistronic, that is they encode several proteins. Each coding sequence in a prokaryotic mRNA has its own initiation and termination codons. 

Another general role of post-translational cleavage of polypeptide chains in viral systems is the specific processing of structural proteins leading to the assembly of the virus (44,45). In this respect, the semliki-Forest virus may be considered as an interesting model to find out how proteins which have different cellular locations reach their final sites within the cell. A single messenger RNA directs the synthesis of the viral capsid protein and of two membrane proteins. 

Lloyd RV, Jin L, Qian X, et al. Analysis of the chromogranin A post-translational cleavage product pancreastatin and the prohormone convertases PC2 and PC3 in normal and neoplastic human pituitaties. Am J Pathol. 1995 146 1188-1198. 

Scott, M.P. R. Jung K. Muntz N.C. Nielsen. A protease responsible for post-translational cleavage of a conserved Asn-Gly linkage in glycinin, the major seed storage protein of soybean. Proc. National Acad. Sci. 1992, 89, 658-662. 

Figure 7.35. Human prion protein single residue hydrophobicity plot. Arrows separated by bar indicate 55 residue sequence that completely forms a P-sheet. Open arrows indicate normal post-translational cleavage sites. Lower arrows indicate...

Thuku, R.N., Weber, B.W., Varsani, A., and Sewell, B.T. (2007) Post-translational cleavage of recombinantly expressed nitrilase from Rhodococcus rhodochrous J1 yields a stable, active helical form. FEBS J., 274, 2099-2108. 

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