Triacylglycerol (TAG) Biosynthesis in Plant Cells

Triacylglycerol biosynthesis is the metabolic process by which cells assemble triacylglycerol (TAG), the main storage lipid, from a glycerol backbone and three fatty acid chains. In plant cells it produces the oils stored in seeds and is carried out mainly through the Kennedy pathway in the endoplasmic reticulum.

The Kennedy pathway is the core route for TAG synthesis. It begins with glycerol-3-phosphate (G3P), which is acylated to lysophosphatidic acid (LPA), then to phosphatidic acid (PA); PA is dephosphorylated to diacylglycerol (DAG), and a final acylation by DGAT adds the third fatty acid to form triacylglycerol (TAG).

In plant cells, fatty acids made in the plastid are exported as acyl-CoA to the endoplasmic reticulum, where the Kennedy pathway sequentially acylates glycerol-3-phosphate through LPA, PA, and DAG to TAG. The finished TAG is then packaged into oil bodies for storage, typically in seeds.

The main steps are: G3P to LPA (catalyzed by GPAT), LPA to PA (LPAAT), PA to DAG (PAP/phosphatidic acid phosphatase), and DAG to TAG (DGAT). Plants also have an acyl-CoA-independent route in which PDAT transfers an acyl group from phospholipids to DAG to form TAG.

In plant cells, the fatty acid building blocks are synthesized in the plastid, but the assembly of triacylglycerol through the Kennedy pathway takes place on the endoplasmic reticulum membrane. The TAG that forms accumulates between the ER membrane leaflets and buds off as oil bodies.

Yes. After generating the pathway you can open it in SciFig's editor to vectorize it into clean SVG, rename each intermediate (G3P, LPA, PA, DAG, TAG), add or remove enzymes such as GPAT and DGAT, and export the figure for a paper, lecture, or poster.