Regulates the composition and fluidity of the plasma membrane (PubMed:30509349). Inhibits the incorporation of membrane-fluidizing phospholipids containing omega-3 long-chain polyunsaturated fatty acids (LCPUFA) and thereby promotes membrane rigidity (PubMed:30509349). Does not appear to have any effect on LCPUFA synthesis (PubMed:30509349). . This is the function of ENSG00000160606 (TLCD1, TLC domain containing 1).