CD79b (Ig beta, B29) forms disulfide-linked heterodimer with CD79a (Ig alpha, MB1). They both are transmembrane proteins with extended cytoplasmic domains containing immunoreceptor tyrosine activation motives (ITAMs), and together with cell surface immunoglobulin they constitute B-cell antigen-specific receptor (BCR). CD79a and b are the first components of BCR that are expressed developmentally. They appear on pro-B cells in association with the endoplasmic reticulum chaperone calnexin. Subsequently, in pre-B cells, CD79 heterodimer is associated with lambda5-VpreB surrogate immunoglobulin and later with antigen-specific surface immunoglobulins. CD79a/b complex interacts with Src-family tyrosine kinase Lyn, which phosphorylates its cytoplasmic ITAM motives to form docking sites for downstream signaling.Specificity :The mouse monoclonal antibody CB3-1 recognizes an extracellular epitope of CD79b (CD79 beta, Ig beta), an approximately 38 kDa component of B cell receptor (BCR) complex.