Acyltransferase which catalyzes the transfert of an acyl group from an acyl-CoA to a lysophosphatidylinositol (1-acylglycerophosphatidylinositol or LPI) leading to the production of a phosphatidylinositol (1,2-diacyl-sn-glycero-3-phosphoinositol or PI) and participates in the reacylation step of the phospholipid remodeling pathway also known as the Lands cycle (PubMed:23097495, PubMed:23472195, PubMed:32253259). Prefers arachidonoyl-CoA as the acyl donor, thus contributing to the regulation of free levels arachidonic acid in cell (PubMed:23097495, PubMed:23472195). In liver, participates in the regulation of triglyceride metabolism through the phosphatidylinositol acyl-chain remodeling regulation (PubMed:32253259). a 1-acyl-sn-glycero-3-phospho-(1D-myo-inositol) + an acyl-CoA = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) + CoA (5Z,8Z,11Z,14Z)-eicosatetraenoyl-CoA + 1-octadecanoyl-sn-glycero-3-phospho-(1D-myo-inositol) = 1-octadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phospho-(1D-myo-inositol) + CoA (5Z,8Z,11Z,14Z)-eicosatetraenoyl-CoA + a 1-acyl-sn-glycero-3-phospho-(1D-myo-inositol) = a 1-acyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phospho-(1D-myo-inositol) + CoA (5Z,8Z,11Z,14Z)-eicosatetraenoyl-CoA + 1-hexadecanoyl-sn-glycero-3-phosphocholine = 1-hexadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphocholine + CoA Lipid metabolism; phospholipid metabolism. Interacts with SPTSSA; the interaction facilitates MBOAT7 location to mitochondria-associated membranes (MAMs). Localized in specific membrane structures termed mitochondria-associated membranes (MAMs) which connect the endoplasmic reticulum (ER) and the mitochondria. Knockout mice die within a month and show atrophy of the cerebral cortex and hippocampus. Embryos at 18.5 dpc have a forebrain smaller in size and show disordered cortical lamination and delayed neuronal migration in the cortex (PubMed:23097495, PubMed:23472195). Mice with conditional knockout in hepatocyte develop hepatic steatosis spontaneously, and hepatic fibrosis on high fat diet feeding (PubMed:32253259). Belongs to the membrane-bound acyltransferase family.