The
tumor necrosis factor receptor superfamily (TNFRSF) is a
group of
cytokine receptors characterized by the ability to bind
tumor necrosis factors (TNFs) via an extracellular
cysteine-rich domain. With the exception of
nerve growth factor (NGF), all TNFs are homologous to the archetypal
TNF-alpha. In their active form, the majority of TNF receptors form trimeric complexes in the plasma membrame. Accordingly, most TNF receptors contain
transmembrane domains (TMDs), although some can be cleaved into soluble forms (e.g.
TNFR1), and some lack a TMD entirely (e.g.
DcR3). In addition, most TNF receptors require specific
adaptor protein such as
TRADD,
TRAF,
RIP and
FADD for downstream signalling. TNF receptors are primarily involved in
apoptosis and
inflammation, but they can also take part in other
signal transduction pathways, such as
proliferation, survival, and
differentiation. TNF receptors are expressed in a wide variety of tissues in mammals, especially in
leukocytes.