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Extracellular Immunoglobulin (Ig) domain of the B and T lymphocyte attenuator (BTLA); member of the I-set Ig superfamily domains The members here are composed of the extracellular immunoglobulin (Ig) domain of the B and T lymphocyte attenuator (BTLA; also known as CD270). BTLA is a type I transmembrane glycoprotein that is structurally similar to the CD28 family of T cell co-stimulatory or coinhibitory molecules. BTLA is a coinhibitory molecule expressed on T cells, B cells, macrophages, dendritic and natural killer (NK) cells. Unlike CD28 family members, BTLA interacts with the tumor necrosis factor receptor superfamily member HVEM (herpes virus entry mediator) rather than with B7 family ligands. In addition, BTLA does not form a homodimer. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. In contrast to CD28 family members, the structure of the BTLA extracellular Ig domain lacks a C" strand and thus is better described as a member of the I-set of Ig domains. I-set domains are found in several cell adhesion molecules, including vascular (VCAM), intercellular (ICAM), neural (NCAM) and mucosal addressin (MADCAM) cell adhesion molecules, as well as junction adhesion molecules (JAM). |
Jiyao W et al.(2023). "The conserved domain database in 2023.",