Cyclooxygenase, mainly comprising two isoforms COX-1 and COX-2, is a membrane-bound enzyme primarily located in the endoplasmic reticulum and nuclear membrane. They catalyze the conversion of arachidonic acid into prostaglandins, participating in biological responses and signaling pathways such as inflammation, pain, and fever. COX-1 is expressed in multiple tissues and is responsible for maintaining physiological functions, while COX-2 is induced during inflammatory responses. Gene-specific expression and mutations affect disease susceptibility and drug responses.