Contents :
Contents Chemistry
Function
History
Biosynthesis and degradation
Antagonists
See also
References
External links
Chemistry :
Chemistry Several molecular species of platelet-activating factor have been identified which vary in the length of the O-alkyl side chain.
Its alkyl group is connected by an ether linkage at the C1 carbon to a sixteen carbon chain.
The acyl group at the C2 carbon is an acetate unit (as opposed to a fatty acid) whose short length increases the solubility of PAF, allowing it to function as a soluble signal messenger.
The C3 has a phosphocholine head group, just like standard phosphatidylcholine
Function :
Function It is an important mediator of bronchoconstriction.
It causes platelets to aggregate and blood vessels to dilate. Thus it is important to the process of hemostasis. At a concentration of 10^-12 M, PAF causes life threatening inflammation of the airways to induce asthma like symptoms.
Toxins such as fragments of destroyed bacteria induce the synthesis of PAF, which causes a drop in blood pressure and reduced volume of blood pumped by the heart, which leads to shock and maybe death.
History :
History It was discovered by French immunologist Jacques Benveniste in the early 1970s.Its structure was elucidated by Constantinos A. Demopoulos in 1979.
Biosynthesis and degradation :
Biosynthesis and degradation PAF is biosynthesized from phosphatidylcholine (LPC) and acetyl CoA by the enzyme LPC acetyltransferase (LPCAT).
It is degraded (thereby terminating its capacity to act as a signaling molecule) by a group of enzymes called PAF acetylhydrolases (PAFAHs) which are related to phospholipase A2.
Platelet-activating factor receptor :
Platelet-activating factor receptor The platelet-activating factor receptor is a G-protein coupled receptor which binds platelet-activating factor.