lecithin-cholesterol acyltransferase (LCAT, phosphatidylcholine-sterol acyltransferase, phospholipid-cholesterol acyltransferase)

Function

• central enzyme in the extracellular metabolism of plasma lipoproteins, especially in the process of reverse cholesterol transport
• esterifies free cholesterol transported in plasma lipoproteins
• LCAT is the only enzyme found in plasma which catalyzes esterfication of sterols
• cholesterol from peripheral cells is transferred to HDL particles, esterified through the action of LCAT on HDL, & incorporated into the core of the lipoprotein
• cholesterol ester is thereby transported back to the liver
• LCAT facilitates the removal of excess cholesterol from peripheral tissues to the liver
• most cholesterol esters present in plasma are the product of the reaction catalyzed by LCAT in which cholesterol is esterified with the sn-2 fatty acid of phosphatidylcholine
• the resulting cholesteryl esters are packed into the hydrophobic core of lipoproteins
• activity is enhanced by apo A1 & inhibited by apo A2

phosphatidylcholine + a sterol
            <-->
1-acylglycerophosphocholine + a sterol ester

Structure

• belongs to the AB hydrolase superfamily, lipase family

Expression

• LCAT is synthesized in the liver & circulates in plasma as a complex with components of high density lipoprotein (HDL).

Pathology

• defects in LCAT are the cause of
  • fish-eye disease [MIM:136120]
  • LCAT deficiency [MIM:245900]; also called Norum disease

More general terms

• cholesterol acyltransferase
• lecithin acyltransferase
• plasma protein
• glycoprotein

Additional terms

• apolipoprotein A1 (APOA1)
• apolipoprotein A2 (APOA2)
• cholesterol
• cholesterol ester
• high density lipoprotein (HDL, alpha-lipoprotein)

Database

• UniProt: http://www.uniprot.org/uniprot/P04180.html
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:3931
• OMIM: https://mirror.omim.org/entry/136120
• OMIM: https://mirror.omim.org/entry/245900
• OMIM: https://mirror.omim.org/entry/606967