B-cell Receptor Overview

RAMs

RAMs

Receptor associated molecules, Ig alpha and Ig beta

ITAMs

Immunoreceptor Tyrosine-Based Activation Motifs, can be phosphorylated to activate B-cells (also present in T-cells) as dimer of Ig alpha and Ig beta

Immature B-cells

Have IgM

Mature (naive) B-cells

Have IgM and IgD

Activated B-cells

Have IgM

Function of ITAMs

Signal transducers because tail of Ig is too short, become phosphorylated and serve as docking sites for adapter molecules

CD21

Membrane bound B-cell coreceptor that helps to bring antigens to BCRs in association with CD19 and CD81

C3d

Serves as a marker that binds antigens and brings them to B-cell receptors (especially B-cell coreceptor CD21), part of the complement system

CD4 ligand

MHC II

CD8 ligand

MHC I

CD2 ligand

CD58

CD28 ligand

CD80, CD86

CTLA-4 ligand

CD80, CD86

CD45R

CD22

CD5

CD72