B cells produce immunoglobulins (Ig, antibodies) that specifically bind antigen molecules. B cells first produce a membrane-bound form of immunoglobulin, the B cell receptor, as part of B cell differentiation. Each B cell expresses one immunoglobulin but the population of B cells in each individual display a wide variety of antigen specificity, with each cell expressing Ig on its surface as part of the B cell receptor complex. When the B cell receptor binds to antigen, it initiates a signal through other proteins non-covalently associated with it in the B cell receptor complex, the Ig-alpha (CD79a) and Ig-beta (CD79b) chains. The signal initiated by binding of antigen to the B cell receptor complex causes growth and proliferation of the B cell and the creation of an amplified clone of effector cells that secrete the antigen-specific immunoglobulin. Activation of the B cell receptor by antigen also results in the production of memory cells that persist in circulation to produce a more rapid immune response after future challenges by the same antigen.

本信号转导涉及的信号分子主要包括：

BCR，mlg，CD19，Ag，CRALChannel，Orai1，Lyn，Ezrin，Syk，SHP-1，SHP-2，SHIP，PTEN，Gab，BACP，Shc，Dok-3，PI3K，PIR-B，Csk，clathrin，Cbp/PAG，Cbl，p38，p70，p85，p110，CD19，CD22，CD40，CD45，Btk，Bam32，PLCγ2，LAB，BLNK，GRB2，SOS，RhoA，Akt，cdc42，Vav，HS1，Pyk2，Rsc，RapL，Riam，Rap，SOS，Rss，c-Raf，MEK1，MEK2，Erk1，Erk2，GRP，Dok-1，IP3R，STIM1，PKC，TAK1，CARMA1，Bcl10，MALT1，IKK，p38，IκB，NF-κB，CaM，GSK-3，mTOR，S6K，Calclneurln，NFAT，MEKK8，MKK3，MKK4，MKK6，MKK7，JNK1，JNK2，CaMK，MEF2C，CREB，ATF-2，Jun，Bcl-6，Egr-1，Elk-1，Bcl-xL，Bfl-1，Oct-2，Ets1，FoxO等。