Translocator protein

Translocator protein (TSPO) is an 18 kDa protein mainly found on the outer mitochondrial membrane. It was first described as peripheral benzodiazepine receptor (PBR), a secondary binding site for diazepam, but subsequent research has found the receptor to be expressed throughout the body and brain. In humans, the translocator protein is encoded by the TSPO gene. It belongs to family of tryptophan-rich sensory proteins. Regarding intramitochondrial cholesterol transport, TSPO has been proposed to interact with StAR (steroidogenic acute regulatory protein) to transport cholesterol into mitochondria, though evidence is mixed.70612257ENSG00000100300ENSMUSG00000041736P30536P50637NM_000714NM_001256530NM_001256531NM_007311NM_009775NP_001243460.1NP_033905In animals, TSPO (PBR) is a mitochondrial protein usually located in the outer mitochondrial membrane and characterised by its ability to bind a variety of benzodiazepine-like drugs, as well as to dicarboxylic tetrapyrrole intermediates of the haem biosynthetic pathway.TSPO is found in many regions of the body including the human iris/ciliary-body. Other tissues include the heart, liver, adrenal and testis, as well as hemopoietic and lymphatic cells. 'Peripheral' benzodiazepine receptors are also found in the brain, although only at around a quarter the expression levels of the 'central' benzodiazepine receptors located at the plasma membrane.TSPO has been shown to be involved in a number of processes such as inflammation, and TSPO ligands may be useful anti-cancer drugs.Ligands of the TSPO are very useful for imaging of inflammation. For example, the radioligand PK-11195 has been used in receptor autoradiography to study neuroinflammation following brain injury. The affinity of PBR28 depends on a single polymorphism (rs6971) in the TSPO gene.