CD40: a member of the TNF-receptor superfamily. This receptor for CD40L mediates a broad variety of immune and inflammatory responses including T cell-dependent immunoglobulin class switching, memory B cell development, and germinal center formation. Defects in CD40 are the cause of hyper-IgM immunodeficiency type 3 (HIGM3). HIGM3 is an autosomal recessive disorder which includes an inability of B cells to undergo isotype switching, one of the final differentiation steps in the humoral immune system, an inability to mount an antibody-specific immune response, and a lack of germinal center formation. Two alternatively spliced isoforms have been reported. Isoform I is a type I membrane protein; isoform II is secreted.
Protein type: Membrane protein, integral; Receptor, cytokine
Chromosomal Location of Human Ortholog: 2 H3|2 85.38 cM
Cellular Component: cell soma; cell surface; cytoplasm; external side of plasma membrane; extracellular space; intracellular membrane-bound organelle; plasma membrane
Molecular Function: antigen binding; enzyme binding; protein binding; protein domain specific binding; tumor necrosis factor receptor activity; ubiquitin protein ligase binding
Biological Process: activation of NF-kappaB transcription factor; B cell activation; cellular calcium ion homeostasis; defense response to protozoan; defense response to virus; immune response-regulating cell surface receptor signaling pathway; inflammatory response; positive regulation of B cell proliferation; positive regulation of GTPase activity; positive regulation of interleukin-12 production; positive regulation of isotype switching to IgG isotypes; positive regulation of MAP kinase activity; positive regulation of MAPKKK cascade; positive regulation of protein amino acid phosphorylation; positive regulation of transcription from RNA polymerase II promoter; positive regulation of tyrosine phosphorylation of Stat1 protein; protein kinase B signaling cascade; regulation of apoptosis; regulation of immune response; regulation of immunoglobulin secretion; response to lipopolysaccharide
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