PLAAT4 (phospholipase A and acyltransferase 4) is a multifunctional enzyme that exhibits dual enzymatic activities in lipid metabolism and plays important roles in tumor suppression and innate immunity. The protein demonstrates both phospholipase A1/A2 activities, catalyzing calcium-independent release of fatty acids from glycerophospholipids, with PLA1 activity being predominant 1. Additionally, PLAAT4 exhibits N-acyltransferase activity, transferring fatty acyl groups from phosphatidylcholine to phosphatidylethanolamine to form N-acylphosphatidylethanolamine (NAPE), a precursor for bioactive N-acylethanolamines 1. The enzyme functions as a tumor suppressor, inducing cell cycle arrest and apoptosis through interaction with the ribosomal protein RPLP0, which mediates decreased cell viability and altered expression of cell cycle and apoptotic proteins 2. PLAAT4 is also involved in antiviral signaling, being transcriptionally regulated by IRF1 and CSNK2B as part of the innate immune response 3. Clinically, PLAAT4 has been identified as a key differentially expressed gene in Alzheimer's disease progression 4, and CAR integration into PLAAT4 has been associated with secondary T cell malignancy development, though this occurs at very low frequency 5. The protein's enzymatic activity is influenced by protein dynamics, particularly in its N-terminal domain 6.