CD40 Active Protein

This gene is a member of the TNF-receptor superfamily. The encoded protein is a receptor on antigen-presenting cells of the immune system and is essential for mediating a broad variety of immune and inflammatory responses including T cell-dependent immunoglobulin class switching, memory B cell development, and germinal center formation. AT-hook transcription factor AKNA is reported to coordinately regulate the expression of this receptor and its ligand, which may be important for homotypic cell interactions. Adaptor protein TNFR2 interacts with this receptor and serves as a mediator of the signal transduction. The interaction of this receptor and its ligand is found to be necessary for amyloid-beta-induced microglial activation, and thus is thought to be an early event in Alzheimer disease pathogenesis. Mutations affecting this gene are the cause of autosomal recessive hyper-IgM immunodeficiency type 3 (HIGM3). Multiple alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported. [provided by RefSeq, Nov 2014]

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: Receptor, cytokine; Membrane protein, integral

Chromosomal Location of Human Ortholog: 20q12-q13.2

Cellular Component: extracellular space; cell surface; intracellular membrane-bound organelle; integral to plasma membrane; cytoplasm; plasma membrane; external side of plasma membrane

Molecular Function: protein binding; signal transducer activity; enzyme binding; ubiquitin protein ligase binding; receptor activity; antigen binding

Biological Process: B cell proliferation; positive regulation of isotype switching to IgG isotypes; platelet activation; regulation of immune response; positive regulation of I-kappaB kinase/NF-kappaB cascade; positive regulation of interleukin-12 production; immune response-regulating cell surface receptor signaling pathway; activation of NF-kappaB transcription factor; cellular calcium ion homeostasis; positive regulation of MAP kinase activity; positive regulation of tyrosine phosphorylation of Stat1 protein; protein kinase B signaling cascade; positive regulation of B cell proliferation; protein complex assembly; positive regulation of transcription from RNA polymerase II promoter; positive regulation of protein amino acid phosphorylation; inflammatory response; defense response to virus; regulation of immunoglobulin secretion

Disease: Immunodeficiency With Hyper-igm, Type 3