GO:0004630 D-type glycerophospholipase activity

D-type glycerophospholipase activity (GO:0004630) is a molecular function in which an enzyme hydrolyses the second phosphodiester bond of a glycerophospholipid, removing the polar head group and releasing phosphatidic acid. This activity is widely known as phospholipase D (PLD) activity and is conserved across prokaryotes and eukaryotes. The term is defined in QuickGO as a glycerophospholipase activity that cleaves the second phosphodiester bond between the phosphate and phospholipid, releasing a phosphatidic acid. Because phosphatidic acid is a potent lipid second messenger, D-type glycerophospholipase activity sits at the intersection of membrane biology, signal transduction and metabolic regulation. Researchers study GO:0004630 to understand how cells remodel membranes, generate lipid signals and coordinate vesicle trafficking. The activity is also a therapeutic target because dysregulated PLD signalling has been implicated in cancer, inflammation and neurodegeneration. This article summarises the definition, mechanism, key genes, disease links and experimental methods for GO:0004630, with a focus on CRISPR-based models that can establish causality.

In plain terms, D-type glycerophospholipase activity is the enzyme function that cuts a phospholipid at its phosphate-head-group bond, releasing phosphatidic acid and a free alcohol. The QuickGO definition states that it is a glycerophospholipase activity that cleaves the second phosphodiester bond between the phosphate and phospholipid, releasing a phosphatidic acid. This is a D-type phospholipase reaction, historically called lecithinase D, choline phosphatase or lipophosphodiesterase II activity. Unlike phospholipase A enzymes that remove acyl chains, D-type glycerophospholipase activity removes the polar head group, so the diacylglycerol backbone remains intact in the phosphatidic acid product.

D-type glycerophospholipase activity is important because it generates phosphatidic acid, a lipid second messenger that controls membrane curvature, vesicle budding, cytoskeletal rearrangements and enzyme recruitment. Because the reaction directly alters the lipid composition of membranes, it influences processes as diverse as secretion, endocytosis, autophagy and cell migration. In disease, altered D-type glycerophospholipase activity has been linked to cancer progression, inflammation and neuronal dysfunction, making it a target for mechanistic and therapeutic studies. Understanding GO:0004630 therefore requires both biochemical assays of enzyme activity and genetic models that test its physiological consequences.

The genes below encode or regulate D-type glycerophospholipase activity and are commonly studied with CRISPR models.

D-type glycerophospholipase activity is regulated at multiple levels. Many PLD enzymes require calcium and acidic phospholipids for catalysis, and their recruitment to membranes is controlled by small GTPases such as ARF and RHO family proteins. Protein kinase C can phosphorylate and activate PLD enzymes, linking GO:0004630 to growth-factor and G-protein-coupled receptor signalling. Phosphatidic acid produced by the reaction can also feed back to regulate the enzyme and its downstream effectors, creating local feedback loops. In addition, expression levels of PLD-family genes are controlled transcriptionally and by microRNAs, so both acute and long-term regulation shape cellular D-type glycerophospholipase activity.

Elevated D-type glycerophospholipase activity and PLD expression have been associated with tumour cell proliferation, survival and invasion. Phosphatidic acid generated by GO:0004630 can activate mitogenic signalling and promote cytoskeletal changes needed for metastasis. CRISPR knockout of PLD genes in cancer cell lines is used to test whether the activity is required for these phenotypes.

PLD-family proteins, including PLD3, have been linked to neuronal membrane homeostasis and to neurodegenerative conditions. Altered D-type glycerophospholipase activity may affect vesicle trafficking and lipid signalling in neurons. Knockout and knock-in models are used to study these neuronal functions.

D-type glycerophospholipase activity contributes to immune cell signalling and inflammatory mediator production. PLD4 and related enzymes are studied in autoimmune and nucleic-acid-sensing pathways. CRISPR models help define which immune functions depend on GO:0004630.

D-type glycerophospholipase activity can be measured using radiolabelled or fluorescent phosphatidylcholine substrates and thin-layer chromatography to detect phosphatidic acid. These assays define the catalytic activity of GO:0004630 in cell lysates or purified enzyme preparations.

Mass spectrometry-based lipidomics quantifies phosphatidic acid and other lipids in cells, providing a readout of D-type glycerophospholipase activity in vivo. This approach is useful for comparing wild-type and CRISPR-edited cells.

Fluorescently tagged PLD enzymes and phosphatidic acid biosensors allow live-cell imaging of where GO:0004630 occurs. Tagged knock-in models preserve endogenous regulation and are ideal for localisation studies.

RNA-seq and proteomics of CRISPR knockout cells reveal downstream pathways controlled by D-type glycerophospholipase activity. These methods connect the molecular function to cellular processes and disease phenotypes.

Researchers studying D-type glycerophospholipase activity-related genes often need to determine whether a candidate gene is causally involved in a phenotype, and CRISPR-based models provide the most direct way to test this. EDITGENE offers a full suite of cell-model engineering services to support such studies.

D-type glycerophospholipase activity (GO:0004630) is a conserved molecular function that generates phosphatidic acid and controls membrane dynamics and lipid signalling. Its roles in cancer, neurodegeneration and immunity make it a compelling target for mechanistic and therapeutic research. CRISPR-based knockout, point-mutation, knock-in and overexpression models are essential tools for establishing causality and translating this activity into disease insights.