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Immune Response
Vertebrates (jawed)
B Cell Receptor Signaling
Antigen-specific activation of B lymphocytes for antibody production.
Overview
The B cell receptor (BCR) is a membrane-bound immunoglobulin that, upon antigen binding, clusters and activates Src-family kinases (Lyn, Fyn) to phosphorylate ITAMs on Igα/Igβ. Syk kinase is recruited and activated, leading to downstream activation of PLCγ2, PI3K, and Ras-MAPK pathways. BTK (Bruton's tyrosine kinase) plays a critical role in PLCγ2 activation and calcium flux.
Cellular Location
B cell membrane → cytoplasm → nucleus
Clinical Significance
Essential for humoral immunity; BTK inhibitors (ibrutinib) revolutionized CLL treatment; PI3Kδ inhibitors used in lymphoma.