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 (biology), homology). Usually this common ancestry is inferred from structural alignment and mechanistic similarity, even if n ...

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 ( ...

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 autocrin ...

. 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 The tumor necrosis factor receptor superfamily (TNFRSF) is a protein superfamily 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 ...

. An occurrence of

orthologs Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a spec ...

in invertebrates hints at ancient origin of this superfamily in evolution. The

PROSITE PROSITE is a protein database. It consists of entries describing the protein families, domains and functional sites as well as amino acid patterns and profiles in them. These are manually curated by a team of the Swiss Institute of Bioinformati ...

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 g ...

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