riproximin

Riproximin is a naturally occurring type II ribosome-inactivating protein (RIP) isolated from the seeds and fruit kernels of the plant Ximenia americana. Structurally, it is a heterodimer consisting of a catalytic A-chain and a lectin-like B-chain linked by a disulfide bridge. The B-chain binds to cell surface glycans (such as NA2/NA3 and clustered Tn structures) and glycoproteins like carcinoembryonic antigen-related cell adhesion molecule (CEACAM), facilitating cellular uptake and internalization of the A-chain. Once inside the cell, the A-chain acts as an rRNA N-glycosidase, depurinating a specific adenine residue in the 28S ribosomal RNA of the large ribosomal subunit, which irreversibly halts protein translation. Riproximin also induces endoplasmic reticulum (ER) stress and activates the unfolded protein response (UPR) pathway, leading to apoptosis and cell cycle arrest. It has demonstrated potent preclinical antineoplastic activity against various solid tumors, including breast, colorectal, and pancreatic cancers.

Other names

RpxRpx-IRpx-IIriproximin protein