Translocator protein

Translocator protein (TSPO) is an 18 kDa protein mainly found on the outer mitochondrial membrane. It interacts with StAR (steroidogenic acute regulatory protein) to transport cholesterol into mitochondria. 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.

Function

In 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 has many proposed functions depending on the tissue. The most studied of these include roles in the immune response, steroid synthesis and apoptosis.