Spike receptor-binding domain, SARS-CoV-2 (RBD (spike RBD or S RBD))

The spike receptor-binding domain (RBD) is a critical structural domain within the SARS-CoV-2 spike glycoprotein that mediates initial viral attachment and entry into host cells[2][4]. Located within the S1 subunit of the trimeric spike protein, the RBD specifically recognizes and binds to the human angiotensin-converting enzyme 2 (ACE2) receptor on target cell surfaces[1][3][4]. Upon ACE2 binding, the RBD undergoes dynamic conformational changes characterized by transitions between "up" (receptor-accessible) and "down" (receptor-inaccessible) conformations, as well as localized structural rearrangements involving secondary structures such as α-helices, β-strands, and κ-helices[1][5][6]. The RBD has emerged as a primary therapeutic target for COVID-19 due to its essential role in viral tropism and its high immunogenicity[8]. Structural studies have revealed that the RBD's binding interface with ACE2 is stabilized by hydrogen bonds, salt bridges, and van der Waals interactions, with conformational changes at a distant hinge region facilitating viral membrane fusion[1]. The RBD is particularly attractive for vaccine development because it is more structurally homogeneous and yields higher expression levels than full-length spike ectodomain[8]. Neutralizing antibodies targeting the RBD can effectively block viral entry, and structure-based drug design efforts have identified potential inhibitors targeting the RBD and nearby polybasic cleavage sites[1][3]. These characteristics make the RBD a high-priority target for therapeutic intervention and vaccine development strategies against SARS-CoV-2 and related coronaviruses[1][2].

Other names

Spike protein receptor-binding domainS protein RBDSARS-CoV-2 RBDRBD domain of spike glycoprotein

ACE2 receptor antagonism (blocking viral attachment); Neutralizing antibody binding; Conformational change inhibition (preventing receptor-induced structural transitions); Polybasic cleavage site targeting (indirect mechanism)