Cox-3

COX-3 is an enzyme that is encoded by the PTGS1 (COX1) gene. It is the third and most recently discovered cyclooxygenase (COX3050) isozyme. COX-3 is not functional in humans.

COX-3 is a splice variant of COX-1 that retains the intron-1 gene sequence at the messenger (m)RNA level. This sequence encodes a 30 amino acid sequence inserted into the N-terminal hydrophobic signal peptide of the enzyme protein.

COX-3 was discovered in the canine cerebral cortex. It is expressed in canine cerebral cortex and in lesser amounts in other tissues analyzed.

Paracetamol can selectively inhibit COX-3 in the brain and spinal cord and thus reduce pain and fever. The exact role of human COX-3 is unclear to date.