Glycerophosphocholines (GP01)

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==Synthesis==
==Synthesis==
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Mammalian cells derive the bulk of their PC from the “Kennedy pathway” described in the work of Kennedy and coworkers almost 40 years ago that is located at the cytosolic side of the endoplasmatic reticulum. Here the first step is the phosphorylation of choline by the enzyme choline kinase (Fig. 24_2).
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Mammalian cells derive the bulk of their PC from the “'''Kennedy pathway'''” described in the work of Kennedy and coworkers almost 40 years ago that is located at the cytosolic side of the endoplasmatic reticulum. Here the first step is the phosphorylation of choline by the enzyme choline kinase (Fig. 24_2).
[[Image:Figure24_2.jpg|frame|center|Figure 24_2. Kennedy Pathway]]
[[Image:Figure24_2.jpg|frame|center|Figure 24_2. Kennedy Pathway]]

Revision as of 09:35, 17 April 2007


Contents

Basics

Phosphatidylcholine is a phospholipid that is a major constituent of cell membranes. Phosphatidylcholine is also known as PtdCho or lecithin.

Structure

LIPID MAPS Phosphatidylcholine generic structure

Natural sources

Phosphatidylcholine

Nomenclature

IUPAC

Glycerophospholipids and subclasses

Synthesis

Mammalian cells derive the bulk of their PC from the “Kennedy pathway” described in the work of Kennedy and coworkers almost 40 years ago that is located at the cytosolic side of the endoplasmatic reticulum. Here the first step is the phosphorylation of choline by the enzyme choline kinase (Fig. 24_2).

Figure 24_2. Kennedy Pathway
Figure 24_2. Kennedy Pathway


The formed phosphocholine is subsequently activated by a phosphate cytidylyltransferase that generates CDP-choline. Finally the enzyme choline phosphotransferase transfers the choline group of CDP-choline to diacylglycerol (DAG) which leads to the formation of PC. Alternatively, phosphatidylethanolamine (PE) is generated via the “Kennedy pathway” employing similar biochemical reaction steps. The PE thus formed can be sequentially methylated on its primary amine using S-adenosylmethionine as the methyl donor by the enzyme PE-N-Methyl-Transferase (PEMT) to form PC after the sequential transfer of 3 methyl groups. These sequential reactions are termed the PEMT pathway.

Both the phosphatidylserine and “Kennedy pathway” are found in mammalian cells but there are some tight restrictions on specific elements of the pathways. In contrast to yeast, the methylation reaction in mammalian cells is not sufficient for supplying all of the PC needed for cell growth.

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