MOLECULES OF THE IMMUNE SYSTEM
Antigen-Recognizing Receptor of B cells (BCR)
An antigen-recognizing B-cell Receptor (BCR) consists of monomeric IgM and IgD and capable of recognizing and binding antigens ("non-self"). BCRs are characterized by cross-linking to antigens. BCR is associated with two specialized accessory molecules, Igα (CD79à+) and Igβ (CD79b+), which are required for signaling and re-expressing BCR.
In addition, there is the coreceptor, CD19+/CD21+/CD81+ that binds to Class II HLA molecules during the recognition of "self".