PK 11195 is an isoquinoline carboxamide which binds selectively to the peripheral benzodiazepine receptor (PBR) (also known as the mitochondrial 18 kDa translocator protein or TSPO).

[2] Early autoradiographic studies using tritiated PK 11195 ([3H]PK 11195) demonstrated that in the central nervous system (CNS) of rodents, it binds primarily to the ependymal walls, choroid plexus, and olfactory bulb.

The binding sites have since been determined to be on glial cells, including microglia, astrocytes, and infiltrating macrophages.

(R)-[11C]PK 11195 has been used in positron emission tomography (PET) scanning to visualize brain inflammation in patients with neuronal damage.

[6][7] The first high-resolution 3D solution structure of mammalian (mouse) translocator protein (TSPO) in a complex with its diagnostic PK 11195 ligand was determined by using NMR spectroscopy techniques by scientists from the Max-Planck Institute for Biophysical Chemistry in Goettingen in Germany in March 2014[8] and has a PDB id: 2MGY.