Lymphotoxin-beta (LT-beta) also known as tumor necrosis factor C (TNF-C) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the ''LTB''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
Function
Lymphotoxin beta is a type II membrane protein of the
TNF family. It anchors
lymphotoxin-alpha to the cell surface through heterotrimer formation. The predominant form on the
lymphocyte
A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic ad ...
surface is the lymphotoxin-alpha 1/beta 2 complex (e.g. 1 molecule alpha/2 molecules beta) and this complex is the primary ligand for the lymphotoxin-beta receptor. The minor complex is lymphotoxin-alpha 2/beta 1. LTB is an inducer of the inflammatory response system and involved in normal development of lymphoid tissue. Lymphotoxin-beta isoform b is unable to complex with lymphotoxin-alpha suggesting a function for lymphotoxin-beta which is independent of lymphotoxin-alpha. Alternative splicing results in multiple transcript variants encoding different isoforms.
Pro-tumorigenic function of membrane LT is clearly established: mice with overexpression of LTα or LTβ showed increased tumor growth and metastasis in several models of cancer. However, these studies utilized mice with complete LTα gene deficiency that did not allow to distinguish effects of soluble versus membrane-associated LT.
Interactions
LTB has been shown to
interact with
Lymphotoxin alpha.
References
Further reading
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{{TNF receptor superfamily modulators
Cytokines