CDPethanolaminvägen

The CDPethanolamine pathway, also known as the Kennedy pathway, is a crucial metabolic route for the de novo synthesis of phosphatidylcholine and phosphatidylethanolamine. These phospholipids are essential components of cell membranes and play vital roles in various cellular processes. The pathway begins with the activation of ethanolamine or choline by phosphorylation, forming ethanolamine-1-phosphate or choline-1-phosphate, respectively. This step is catalyzed by the enzyme ethanolamine kinase or choline kinase.

Next, the phosphorylated alcohol is activated by reacting with cytidine triphosphate (CTP) to form cytidine diphosphate-ethanolamine (CDP-ethanolamine) or cytidine diphosphate-choline (CDP-choline). This reaction is mediated by CTP:phosphoethanolamine cytidylyltransferase or CTP:phosphocholine cytidylyltransferase. Finally, CDP-ethanolamine or CDP-choline is transferred to a diacylglycerol molecule to form phosphatidylethanolamine or phosphatidylcholine. This reaction is catalyzed by CDP-ethanolamine:1,2-diacylglycerol phosphoethanolamine transferase or CDP-choline:1,2-diacylglycerol phosphocholine transferase.

The CDPethanolamine pathway is particularly important in the liver, where it is a primary source of phosphatidylcholine synthesis. Phosphatidylcholine is a component of bile and is essential for fat absorption. In other tissues, the pathway contributes to membrane structure and function. While the Kennedy pathway is a significant source of these phospholipids, alternative pathways, such as the methylation of phosphatidylethanolamine, also exist for phosphatidylcholine synthesis. The regulation of the CDPethanolamine pathway is tightly controlled to meet the cell's demands for phospholipids.