Spike glycoprotein receptor binding domain (S1 RBD), SARS-CoV-2 spike protein receptor binding domain (Spike RBD, S1 RBD)

The Spike glycoprotein receptor binding domain (S1 RBD) is a region of the SARS-CoV-2 Spike (S) protein that mediates viral attachment by binding to the primary host cell receptor angiotensin-converting enzyme 2 (ACE2). The S protein is a trimeric, type I viral fusion protein present on the viral surface, with S1 containing the RBD and S2 mediating membrane fusion. The S1 RBD (~residues 319–541) specifically interacts with ACE2 on the surface of human cells, initiating viral entry and infection. The domain exists in dynamic conformations (“up” and “down”) that regulate its accessibility. The RBD is the principal target for neutralizing antibodies in natural infection and vaccines. Many variants of concern (e.g., Delta, Omicron) exhibit mutations in the RBD, impacting infectivity and immune escape. Its central role in viral entry and immunogenicity make the S1 RBD an essential therapeutic and diagnostic target.

Other names

S1 receptor binding domainSpike RBDReceptor binding motifSARS-CoV-2 S protein RBDS1 CTD

Inhibition of receptor binding (antibodies bind RBD, preventing interaction with ACE2); Immune neutralization (antibody binding leads to viral neutralization); Receptor decoy blockade (recombinant ACE2 competes for RBD binding)