4-1BB

About 4-1BB:

4-1BBL also called 4-1BB Ligand and CD137L, CD137 Ligand, TNFSF9 binds to 4-1BBR also called 4-1bb Receptor and CD137, TNFRSF9.  4-1BBL stimulates the growth of activated peripheral blood T-cells. 4-1BB Ligand takes part in initialization of induced cell death aka AICD.4-1BBL is also involved in cognate interactions among T-cells and B-cells aka macrophages. 4-1BBL antigen is a type 2 transmembrane glycoprotein which is part of the TNF superfamily that is expressed on activated T Lymphocytes. 

The absence of 4-1BBR in murine subjects demonstrate augmented T cell activation, which results due to the lack of CD137 in regulatory T cells. 4-1BB participates along with OX40 on activated T cells, establishing a complex that prevents Treg and CD8+ T cell production. CD137L is a two directional signal transducer that has a role as a ligand to TNFRSF9 aka 4-1BBR, which is a co-stimulation receptor protein in T lymphocytes. TNFSF9 and TNFRSF9 take part in the antigen demonstration development and in the induction of cytotoxic T cells. 4-1BBR is promptly produced upon antigenic stimulation but is absent from latent T lymphocytes. TNFSF9 revives anergic T lymphocytes furthermore to promoting T lymphocyte proliferation. 4-1BBL is essential for CD8 optimal reactions in CD8 T cells. CD137L is produced in carcinoma cell lines, and is thought to be involved in T cell-tumor cell interaction. 

4-1BBR, is located on the cell surface in the immune system. 4-1BB-L is absent of a signal sequence and N-linked glycosylation domain, however comprises a ser/pro-rich site proximal to the transmembrane region which is comprised of O-linked carbohydrates. CD137 increases T cell production, IL-2 discharge, survival and cytolytic activity. CD137 increases immune activity to remove tumors in mice. TRAF adaptor proteins bind to CD137 and transduce the signals which results to the activation of NF-kappaB.