CD40 (Tumor Necrosis Factor Receptor Superfamily Member 5, B-cell Surface Antigen CD40, Bp50, CD40L Receptor, CDw40, TNFRSF5)

CD40 and its ligand CD154 are members of the tumor necrosis factor receptor (TNFR) and TNF families, respectively, that play key roles in signaling pathways mediating cell growth, survival and differentiation in B-lymphocytes (reviewed in Quezada et al 2004). The CD40 receptor is a 45-50kD glycoprotein and is expressed on the surface of B-lymphocytes, some activated T-cells, monocytes, follicular dendritic cells, basal epithelial cells, and in some epithelial and non-epithelial carcinomas. The functions of CD40 have been most extensively studied in B-cells. Ligation of B CD40 by CD154, expressed on activated T cells, stimulates B cell proliferation, differentiation, isotype switching, upregulation of surface molecules contributing to antigen presentation, development of the germinal center, and the humoral memory response. Several distinct structural motifs in the CD40 cytoplasmic domain regaulate various CD40 signaling pathways. A major CD40 signaling pathway activated from CD154 ligand binding is the canonical pathway to the transcription factor family NF-kB, a family of genes mediating immune and inflammatory responses. Although CD40 has been extensively studied as a plasma membrane-associated growth factor membrane receptor. It has also been identified in the cytoplasm and nucleus of normal and neoplastic B-lymphoid cells (Lin-Lee et al. 2006). Other growth factor receptors, including EGF, FGF, and TGF-B have also been identified in the nuclus. It is thought that plasma membrane receptor signaling may be followed by nuclear migration of signaling pathway components. The presence of CD40 in the nucleus of activated normal B lymphocytes and neoplastic B-lymphoid cells suggests that CD40 may play a more complex role in regulating essential growth and survival pathways in B-lymphocytes than previously thought. Applications: Suitable for use in Western Blot, Immunohistochemistry and Immunoprecipitation. Other applications not tested. Recommended Dilution: Western Blot: 1:1000-1:2000 Immunohistochemistry (formalin fixed paraffin embedded): 1:1000-1:5000 Immunoprecipitation: 1:50-1:200 Immunohistochemistry: Frozen Optimal dilutions to be determined by the researcher. Positive Control: Spleen, tonsil Storage and Stability: May be stored at 4 degrees C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Aliquots are stable for at least 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.