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FUNCTION Calcium-independent phospholipase, lysophospholipase and O-acyltransferase involved in phospholipid remodeling with implications in endoplasmic reticulum membrane homeostasis and lipid droplet biogenesis (PubMed:10085124, PubMed:10358058, PubMed:19501189, PubMed:28336330, PubMed:9705332). Preferentially hydrolyzes the ester bond of the fatty acyl group attached at the sn-2 position of phospholipids with choline and ethanolamine head groups, producing lysophospholipids that are used in deacylation-reacylation cycles (PubMed:10085124, PubMed:10358058, PubMed:19501189, PubMed:28336330, PubMed:9705332). Transfers the sn-1 fatty acyl from one lysophospholipid molecule to the sn-2 position of another lysophospholipid to form diacyl, alkylacyl and alkenylacyl glycerophospholipids. Cleaves ester bonds but not alkyl or alkenyl ether bonds at sn-1 position of lysophospholipids (PubMed:15944408, PubMed:19501189). Catalyzes sn-2 fatty acyl transfer from phospholipids to the sn-2 position of 1-O-alkyl or 1-O-alkenyl lysophospholipids with lower efficiency (PubMed:15944408, PubMed:19501189). In response to dietary fatty acids, may play a role in the formation of nascent lipid droplets from the endoplasmic reticulum likely by regulating the phospholipid composition of these organelles (PubMed:28336330).FUNCTION (Microbial infection) May play a role in replication and assembly of human hepatitis C virus (HCV) (PubMed:23015700, PubMed:28336330). In response to HCV infection, promotes remodeling of host endoplasmic reticulum membranes to form organelle-like structures called membranous web, where HCV replication occur (PubMed:23015700). Can further mediate translocation of replication complexes to lipid droplets to enable virion assembly (PubMed:23015700, PubMed:28336330).FUNCTION (Microbial infection) May facilitate human T-lymphotropic virus type 1 (HTLV-1) infection by promoting leukotriene B4 (LTB4) biosynthesis. LTB4 acts as a chemoattractant for HTLV-1-infected CD4-positive T cells and favors cell to cell viral transmission.CATALYTIC ACTIVITY a 1,2-diacyl-sn-glycero-3-phosphocholine + H2O = a 1-acyl-sn-glycero-3-phosphocholine + a fatty acid + H(+)CATALYTIC ACTIVITY a 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine + H2O = a 1-O-alkyl-sn-glycero-3-phosphocholine + a fatty acid + H(+)CATALYTIC ACTIVITY 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine + H2O = 1-hexadecanoyl-sn-glycero-3-phosphocholine + hexadecanoate + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-2-(9Z-octadecenoyl)-sn-glycero-3-phosphocholine + H2O = 1-hexadecanoyl-sn-glycero-3-phosphocholine + (9Z)-octadecenoate + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-2-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphocholine + H2O = (9Z,12Z)-octadecadienoate + 1-hexadecanoyl-sn-glycero-3-phosphocholine + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphocholine + H2O = 1-hexadecanoyl-sn-glycero-3-phosphocholine + (5Z,8Z,11Z,14Z)-eicosatetraenoate + H(+)CATALYTIC ACTIVITY 1-O-hexadecyl-2-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-sn-glycero-3-phosphocholine + H2O = 1-O-hexadecyl-sn-glycero-3-phosphocholine + (5Z,8Z,11Z,14Z)-eicosatetraenoate + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphocholine + H2O = 2-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-sn-glycero-3-phosphocholine + hexadecanoate + H(+)CATALYTIC ACTIVITY a 1-acyl-sn-glycero-3-phosphocholine + H2O = sn-glycerol 3-phosphocholine + a fatty acid + H(+)CATALYTIC ACTIVITY 1-hexadecanoyl-sn-glycero-3-phosphocholine + H2O = sn-glycerol 3-phosphocholine + hexadecanoate + H(+)CATALYTIC ACTIVITY 2 1-hexadecanoyl-sn-glycero-3-phosphocholine = 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine + sn-glycerol 3-phosphocholineCATALYTIC ACTIVITY 1-hexadecanoyl-sn-glycero-3-phosphoethanolamine + 1-hexadecanoyl-sn-glycero-3-phosphocholine = 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine + sn-glycerol 3-phosphocholineCATALYTIC ACTIVITY 1-hexadecanoyl-sn-glycero-3-phosphoethanolamine + 1-hexadecanoyl-sn-glycero-3-phosphocholine = sn-glycero-3-phosphoethanolamine + 1,2-dihexadecanoyl-sn-glycero-3-phosphocholineCATALYTIC ACTIVITY 2 1-hexadecanoyl-sn-glycero-3-phosphoethanolamine = 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine + sn-glycero-3-phosphoethanolamineCATALYTIC ACTIVITY 1-O-hexadecyl-sn-glycero-3-phosphocholine + 1-hexadecanoyl-sn-glycero-3-phosphocholine = 1-O-hexadecyl-2-hexadecanoyl-sn-glycero-3-phosphocholine + sn-glycerol 3-phosphocholineCATALYTIC ACTIVITY a 1-O-(1Z-alkenyl)-sn-glycero-3-phosphoethanolamine + 1-hexadecanoyl-sn-glycero-3-phosphocholine = 1-O-(1Z)-alkenyl-2-hexadecanoyl-sn-glycero-3-phosphoethanolamine + sn-glycerol 3-phosphocholineCATALYTIC ACTIVITY 1-O-hexadecyl-sn-glycero-3-phosphocholine + 1-hexadecanoyl-sn-glycero-3-phosphoethanolamine = 1-O-hexadecyl-2-hexadecanoyl-sn-glycero-3-phosphocholine + sn-glycero-3-phosphoethanolamineCATALYTIC ACTIVITY 1-octadecanoyl-2-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-sn-glycero-3-phosphoethanolamine + 1-hexadecanoyl-sn-glycero-3-phosphocholine = 1-octadecanoyl-sn-glycero-3-phosphoethanolamine + 1-hexadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphocholineCATALYTIC ACTIVITY 1-octadecanoyl-2-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-sn-glycero-3-phosphoethanolamine + 1-O-hexadecyl-sn-glycero-3-phosphocholine = 1-octadecanoyl-sn-glycero-3-phosphoethanolamine + 1-O-hexadecyl-2-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-sn-glycero-3-phosphocholineCATALYTIC ACTIVITY 1-hexadecanoyl-2-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphocholine + a 1-O-(1Z-alkenyl)-sn-glycero-3-phosphoethanolamine = 1-O-(1Z-alkenyl)-2-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphoethanolamine + 1-hexadecanoyl-sn-glycero-3-phosphocholineCATALYTIC ACTIVITY 1-hexadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphocholine + a 1-O-(1Z-alkenyl)-sn-glycero-3-phosphoethanolamine = 1-O-(1Z)-alkenyl-2-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-sn-glycero-3-phosphoethanolamine + 1-hexadecanoyl-sn-glycero-3-phosphocholineACTIVITY REGULATION Not regulated by calcium, coenzyme A or ATP (PubMed:10085124, PubMed:15944408, PubMed:9705332). Lysophospholipase activity is inhibited by palmitoyl-CoA (PubMed:14529291). Lysophospholipase and O-acyltransferase activities are inhibited by methylarachidonoylfluorophosphonate (PubMed:19501189). Lysophospholipase activity is inhibited by phosphatidate or lysophosphatidate (PubMed:19501189). O-acyltransferase activity is up-regulated at low concentration (10-20 uM) of phosphatidate or lysophosphatidate, but inhibited at higher concentrations (PubMed:19501189).BIOPHYSICOCHEMICAL PROPERTIES Optimum pH is 6.5 for lysophospholipase activity, and 8-9 for O-acyltransferase activity.SUBUNIT (Microbial infection) Interacts with HCV non-structural protein 4B/NS4B; this interaction likely initiates the recruitment of replication complexes to lipid droplets.INTERACTION Translocates from endoplasmic reticulum to lipid droplets in response to oleate.ALTERNATIVE PRODUCTS Highly expressed in heart and skeletal muscle.INDUCTION (Microbial infection) Up-regulated by HCV.INDUCTION (Microbial infection) Transcriptionally up-regulated by HTLV-1 Tax.
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