The tumor necrosis factor (TNF) superfamily is a
protein superfamily
A protein superfamily is the largest grouping (clade) of proteins for which common ancestry can be inferred (see homology). Usually this common ancestry is inferred from structural alignment and mechanistic similarity, even if no sequence similar ...
of
type II transmembrane proteins containing TNF homology domain and forming
trimers. Members of this superfamily can be released from the
cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...
by extracellular
proteolytic cleavage
Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, ...
and function as a
cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in au ...
. These proteins are expressed predominantly by immune cells and they regulate diverse cell functions, including immune response and inflammation, but also proliferation, differentiation, apoptosis and embryogenesis.
The superfamily contains 19 members that bind to 29 members of
TNF receptor superfamily.
An occurrence of
orthologs in invertebrates hints at ancient origin of this superfamily in evolution.
The
PROSITE pattern of this superfamily is located in a
beta sheet
The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a ge ...
in the central section of the protein that is conserved across all members.
Members
There are 19 family members, numerically classified as TNFSF#, where # denotes the member number, sometimes followed by a letter.
*
References
External links
*
pex1 tumor necrosis factor gene
{{Authority control
Cytokines
Protein superfamilies
Single-pass transmembrane proteins
TNF receptor family