Phosphatidylcholine-sterol acyltransferase (LCAT)

The protein contains 440 amino acids for an estimated molecular weight of 49578 Da.

 

Central enzyme in the extracellular metabolism of plasma lipoproteins. Synthesized mainly in the liver and secreted into plasma where it converts cholesterol and phosphatidylcholines (lecithins) to cholesteryl esters and lysophosphatidylcholines on the surface of high and low density lipoproteins (HDLs and LDLs) (PubMed:10329423, PubMed:19065001, PubMed:26195816). The cholesterol ester is then transported back to the liver. Has a preference for plasma 16:0-18:2 or 18:O-18:2 phosphatidylcholines (PubMed:8820107). Also produced in the brain by primary astrocytes, and esterifies free cholesterol on nascent APOE-containing lipoproteins secreted from glia and influences cerebral spinal fluid (CSF) APOE- and APOA1 levels. Together with APOE and the cholesterol transporter ABCA1, plays a key role in the maturation of glial-derived, nascent lipoproteins. Required for remodeling high-density lipoprotein particles into their spherical forms (PubMed:10722751). Catalyzes the hydrolysis of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet-activating factor or PAF) to 1-O-alkyl-sn-glycero-3-phosphocholine (lyso-PAF) (PubMed:8016111). Also catalyzes the transfer of the acetate group from PAF to 1-hexadecanoyl-sn-glycero-3-phosphocholine forming lyso-PAF (PubMed:8016111). Catalyzes the esterification of (24S)-hydroxycholesterol (24(S)OH-C), also known as cerebrosterol to produce 24(S)OH-C monoesters (PubMed:24620755). (updated: June 17, 2020)

Protein identification was indicated in the following studies:

  1. D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.

Methods

The following articles were analysed to gather the proteome content of erythrocytes.

The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.

PublicationIdentification 1Uniprot mapping 2Not mapped /
Obsolete
TrEMBLSwiss-Prot
Goodman (2013)2289 (gene list)227853205992269
Lange (2014)123412347281224
Hegedus (2015)2638262202352387
Wilson (2016)165815281702911068
d'Alessandro (2017)18261817201815
Bryk (2017)20902060101081942
Chu (2018)18531804553621387

1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry

The compilation of older studies can be retrieved from the Red Blood Cell Collection database.

The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.

No sequence conservation computed yet.

Interpro domains
Total structural coverage: 0%
Model score: 100
No model available.

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VariantDescription
LCATD
FED
FED
LCATD
LCATD
LCATD
FED
Found in a patient with intermediate phenotype between LCATD and FED; reduction of activity
FED; loss of activity
dbSNP:rs1412883954
LCATD
FED
FED
FED
LCATD
LCATD
LCATD
dbSNP:rs1369994093
LCATD
LCATD
dbSNP:rs387906300
LCATD
dbSNP:rs4986970
LCATD
LCATD
a patient with low HDL-cholesterol levels; the mutant is hardly secreted and is catalytically inactive
LCATD
a patient with low HDL-cholesterol levels
LCATD
FED
FED and LCATD
LCATD
LCATD
a patient with low HDL-cholesterol levels
LCATD
LCATD
FED
LCATD
FED
FED
a patient with LCATD
LCATD

The reference OMIM entry for this protein is 136120

Fish-eye disease; fed
Dyslipoproteinemic corneal dystrophy
Alpha-lecithin:cholesterol acyltransferase deficiency
Alpha-lcat deficiency
Lcata deficiency

A number sign (#) is used with this entry because fish-eye disease is caused by mutation in the lecithin:cholesterol acyltransferase gene (LCAT; 606967), which is also the site of mutation in Norum disease (245900).

CLINICAL FEATURES

In Sweden, Carlson and Philipson (1979) described a man and his 3 daughters with a disorder called 'fish-eye' in their home village because corneal opacities gave their eyes the appearance of those of boiled fish. Two living sisters showed the same dyslipoproteinemia, characterized by normal serum cholesterol but raised serum triglycerides, raised VLDL, and strikingly high LDL triglycerides. In HDL, cholesterol was reduced. Corneal opacities (of less dense nature) occur in Tangier disease (HDLDT1; 205400) and LCAT deficiency (Norum disease), but both of these were excluded by normal electrophoretic mobility of HDL and normal LCAT activity, respectively. Visual impairment was almost the only clinical problem. Carlson (1979) reported a second case, in a 70-year-old woman referred to him by ophthalmologist Philipson. The woman was in general good health. Corneal clouding was noted before age 20, but she worked as a hairdresser until age 65. Parents and 5 sibs were free of eye disease. Cases of fish eye disease were also observed in Canada by Frohlich et al. (1987); Kastelein et al. (1992) stated that the father's maternal side of the family had been traced back to Sweden. A fourth family of Dutch descent was reported by Kastelein et al. (1992). Funke et al. (1991) described the biochemical and genetic presentation of 2 homozygotes from a German family with fish-eye disease and their relatives. They demonstrated vertical transmission of a decrease in the specific activity of LCAT. Two brothers, 57 and 68 years old, had massive bilateral corneal opacities that almost completely covered the irides. There were several consanguineous marriages in their family history. In their village, the kindred was known to have been affected with 'sick eyes' for several generations. The younger brother suffered from angiographically assessed 2-vessel coronary disease, and the elder brother suffered from angina pectoris. Family history, however, was not compatible with an increased prevalence of myocardial infarction. All 5 children of the 2 presumed homozygotes were heterozygotes.

PATHOGENESIS

Carlson and Holmquist (1985) and Holmquist and Carlson (1987) demonstrated that the defect in fish-eye disease is deficiency of high density lipoprotein lecithin:cholesterol acyltransferase activity. Alpha-LCAT, deficient in this condition, is specific for HDL, whereas beta-LCAT, also deficient in Norum disease (245900), is specific for combined VLDL and LDL (Carlson and Holmquist, 1985). Thus, fish-eye disease is one form of LCAT deficiency. In fish-eye disease, the HDL of plasma contains only about 20% cholesteryl esters relative to total cholesterol as compared to 75 to 80% in control HDL. In fish-eye disease plasma, however, there is a normal cholesteryl ester percentage as well as a normal plasma cholesterol esterification rate as a result of the activity of beta-LCAT.

MOLECULAR GENETICS

By restriction enzyme analysis of the apoA-I gene, Rees et al. (1984) could demonstrate no major deletion or insertion in 2 patients with fish-eye disease. The mutations in fish-eye disease and in Norum disease are in the same gene, that encoding LCAT, located on chromosome 16. In the family described by Funke et al. ... More on the omim web site

Subscribe to this protein entry history

June 29, 2020: Protein entry updated
Automatic update: Entry updated from uniprot information.

Oct. 20, 2018: Protein entry updated
Automatic update: OMIM entry 136120 was added.

Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).