Ribosome-inactivating proteins: current status and biomedical applications

Ribosome-inactivating proteins (RIPs) are mainly present in plants and function to inhibit protein synthesis through the removal of adenine residues from eukaryotic ribosomal RNA (rRNA). They are broadly classified into two groups: type I and type II. Type I RIPs are a diverse family of proteins comprising a single polypeptide chain, whereas type II RIPs are heterodimeric glycoproteins comprising an A-chain (functionally equivalent to a type I RIP) linked via a disulphide bond to a B chain, mediating cell entry. In this review, we describe common type I and type II RIPs, their diverse biological functions, mechanism of cell entry, stability in plasma and antigenicity. We end with a discussion of promising applications for RIPs in biomedicine.

► RIPs are capable of depurinating both prokaryotic and eukaryotic ribosomes.
► RIPs have been shown to inhibit HIV replication and integration; however its usage as drugs is still in its relative infancy.
► Biomedical application of RIPs in viral diseases prevention are discussed in this review.
► Promising structural data on RIPs will lead to development of small HIV-inhibiting molecules.