Phosphatidylserine
Phosphatidylserine (PS or PtdSer) is a phospholipid nutrient found in fish, green leafy vegetables, soybeans, and rice, and is essential for the normal functioning of neuronal cell membranes, activating protein kinase C (PKC), which has been shown to be involved in memory function. [1] Phosphatidylserine is usually kept on the inner-leaflet of cell membranes by any enzyme called translocase. In apoptosis, caspase 3 activation culminates in deactivation of translocase and activation of scramblase which allows free movement of PtdSer down its concentration gradient and floppase which transports it to the outer leaflet of the plasma membrane. This is part of the process by which the cell is targeted for phagocytosis.
Applications
Research
Annexin-A5 is a naturally-occurring protein with avid binding affinity for PS. Labeled-annexin-A5 enables visualization of cells in the early-mid apoptotic state in vitro or in vivo.
PS has been shown to slow cognitive decline in animal models.[2]
PS has been investigated in a small number of double-blind placebo trials and has been shown to increase memory performance in the elderly. Because of the potential cognitive benefits of phosphatidylserine, the substance is sold as a dietary supplement to people that believe they can benefit from an increased intake.
The dietary supplement was originally processed from bovine sources, however Prion disease scares in the 1990s outlawed this process, and a soy-based alternative was adopted.[3]
References
1. ^ Micheau J, Riedel G. (Apr 1999). "Protein kinases: which one is the memory molecule?". Cell Mol Life Sci. 55 (4): 534-48. PubMed. Retrieved on 2007-09-25.
2. ^ McDaniel MA, Maier SF, Einstein GO. (Nov-Dec 2003). ""Brain-specific" nutrients: a memory cure?". Nutrition 19 (11-12): 957-75. PubMed.
3. ^ Kingsley M. (2006). "Effects of phosphatidylserine supplementation on exercising humans". Sports Medicine 36 (8): 657-69. PubMed.