Red blood cell surface lysine residues on outward-facing membrane proteins (RBC surface lysines)

Red blood cell (RBC) surface lysine residues on outward-facing membrane proteins serve as a critical target for covalent bioconjugation and drug delivery strategies. These residues are primarily located on the extracellular domains of abundant membrane proteins, most notably Band 3 (Anion Exchanger 1) and Glycophorins A and B, which provide millions of potential attachment sites per cell (Villa et al., 2016). By employing amine-reactive chemistries, such as N-hydroxysuccinimide (NHS) esters or aldehydes, researchers can attach therapeutic enzymes, nanoparticles, or polymers like polyethylene glycol (PEG) directly to the RBC surface (Muzykantov, 2010). This approach, often termed RBC hitchhiking, leverages the erythrocyte natural 120-day lifespan to extend the circulation time of drugs and can be used to target specific vascular beds, such as the pulmonary vasculature (Brenner et al., 2018). While not a traditional signaling receptor, these lysine residues are essential for immunocamouflage techniques and the development of long-acting erythrocyte-based therapeutics.

Other names

Erythrocyte surface lysinesRBC membrane protein lysinesSurface-exposed lysines on RBCsExtracellular lysine residues of RBC membrane proteins

Covalent modification via amine-reactive chemistry (e.g., NHS-ester reaction or aldehyde-mediated Schiff base formation) to utilize erythrocytes as long-circulating drug carriers or to mask surface antigens.