APOE_EREDO
ID APOE_EREDO Reviewed; 299 AA.
AC P0DUY8;
DT 23-FEB-2022, integrated into UniProtKB/Swiss-Prot.
DT 23-FEB-2022, sequence version 1.
DT 03-AUG-2022, entry version 3.
DE RecName: Full=Apolipoprotein E;
DE Short=Apo-E;
DE Flags: Precursor;
GN Name=APOE;
OS Erethizon dorsatum (North American porcupine).
OC Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC Eutheria; Euarchontoglires; Glires; Rodentia; Hystricomorpha;
OC Erethizontidae; Erethizon.
OX NCBI_TaxID=34844;
RN [1]
RP NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC TISSUE=Blood;
RA Kirk H., Pandoh P., Troussard A., Zhao Y., Mungall A., Moore R.,
RA Sinclair-Smith T., Desprez I., Parker D., Marra M.A., Jones S.J.M.;
RT "The genome of the North American Porcupine (Erethizon dorsatum).";
RL Submitted (APR-2019) to the EMBL/GenBank/DDBJ databases.
RN [2]
RP IDENTIFICATION.
RA Puppione D.L.;
RL Unpublished observations (JUL-2021).
CC -!- FUNCTION: APOE is an apolipoprotein, a protein associating with lipid
CC particles, that mainly functions in lipoprotein-mediated lipid
CC transport between organs via the plasma and interstitial fluids. APOE
CC is a core component of plasma lipoproteins and is involved in their
CC production, conversion and clearance. Apoliproteins are amphipathic
CC molecules that interact both with lipids of the lipoprotein particle
CC core and the aqueous environment of the plasma. As such, APOE
CC associates with chylomicrons, chylomicron remnants, very low density
CC lipoproteins (VLDL) and intermediate density lipoproteins (IDL) but
CC shows a preferential binding to high-density lipoproteins (HDL). It
CC also binds a wide range of cellular receptors including the LDL
CC receptor/LDLR, the LDL receptor-related proteins LRP1, LRP2 and LRP8
CC and the very low-density lipoprotein receptor/VLDLR that mediate the
CC cellular uptake of the APOE-containing lipoprotein particles. Finally,
CC APOE has also a heparin-binding activity and binds heparan-sulfate
CC proteoglycans on the surface of cells, a property that supports the
CC capture and the receptor-mediated uptake of APOE-containing
CC lipoproteins by cells. A main function of APOE is to mediate
CC lipoprotein clearance through the uptake of chylomicrons, VLDLs, and
CC HDLs by hepatocytes. APOE is also involved in the biosynthesis by the
CC liver of VLDLs as well as their uptake by peripheral tissues ensuring
CC the delivery of triglycerides and energy storage in muscle, heart and
CC adipose tissues. By participating in the lipoprotein-mediated
CC distribution of lipids among tissues, APOE plays a critical role in
CC plasma and tissues lipid homeostasis. APOE is also involved in two
CC steps of reverse cholesterol transport, the HDLs-mediated transport of
CC cholesterol from peripheral tissues to the liver, and thereby plays an
CC important role in cholesterol homeostasis. First, it is functionally
CC associated with ABCA1 in the biogenesis of HDLs in tissues. Second, it
CC is enriched in circulating HDLs and mediates their uptake by
CC hepatocytes. APOE also plays an important role in lipid transport in
CC the central nervous system, regulating neuron survival and sprouting.
CC {ECO:0000250|UniProtKB:P02649}.
CC -!- SUBUNIT: Homotetramer. May interact with ABCA1; functionally associated
CC with ABCA1 in the biogenesis of HDLs. May interact with APP/A4 amyloid-
CC beta peptide; the interaction is extremely stable in vitro but its
CC physiological significance is unclear. May interact with MAPT. May
CC interact with MAP2. In the cerebrospinal fluid, interacts with secreted
CC SORL1. {ECO:0000250|UniProtKB:P02649}.
CC -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250|UniProtKB:P02649}.
CC Secreted, extracellular space {ECO:0000250|UniProtKB:P02649}. Secreted,
CC extracellular space, extracellular matrix
CC {ECO:0000250|UniProtKB:P02649}. Note=In the plasma, APOE is associated
CC with chylomicrons, chylomicrons remnants, VLDL, LDL and HDL
CC lipoproteins. Lipid poor oligomeric APOE is associated with the
CC extracellular matrix in a calcium- and heparan-sulfate proteoglycans-
CC dependent manner. Lipidation induces the release from the extracellular
CC matrix. {ECO:0000250|UniProtKB:P02649}.
CC -!- PTM: APOE exists as multiple glycosylated and sialylated glycoforms
CC within cells and in plasma. The extent of glycosylation and sialylation
CC are tissue and context specific. {ECO:0000250|UniProtKB:P02649}.
CC -!- PTM: Glycated in plasma VLDL. {ECO:0000250|UniProtKB:P02649}.
CC -!- PTM: Phosphorylated by FAM20C in the extracellular medium.
CC {ECO:0000250|UniProtKB:P02649}.
CC -!- SIMILARITY: Belongs to the apolipoprotein A1/A4/E family.
CC {ECO:0000305}.
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DR EMBL; SWEC01025652; -; NOT_ANNOTATED_CDS; Genomic_DNA.
DR GO; GO:0042627; C:chylomicron; IEA:UniProtKB-KW.
DR GO; GO:0034364; C:high-density lipoprotein particle; IEA:UniProtKB-KW.
DR GO; GO:0034361; C:very-low-density lipoprotein particle; IEA:UniProtKB-KW.
DR GO; GO:0008201; F:heparin binding; IEA:UniProtKB-KW.
DR GO; GO:0008289; F:lipid binding; IEA:UniProtKB-KW.
DR GO; GO:0006869; P:lipid transport; IEA:UniProtKB-KW.
DR GO; GO:0042157; P:lipoprotein metabolic process; IEA:InterPro.
DR InterPro; IPR000074; ApoA_E.
DR Pfam; PF01442; Apolipoprotein; 1.
PE 3: Inferred from homology;
KW Chylomicron; Extracellular matrix; Glycoprotein; HDL; Heparin-binding;
KW Lipid transport; Lipid-binding; Oxidation; Phosphoprotein; Repeat;
KW Secreted; Signal; Transport; VLDL.
FT SIGNAL 1..18
FT /evidence="ECO:0000255"
FT CHAIN 19..299
FT /note="Apolipoprotein E"
FT /id="PRO_0000454012"
FT REPEAT 74..95
FT /note="1"
FT REPEAT 96..117
FT /note="2"
FT REPEAT 118..139
FT /note="3"
FT REPEAT 140..161
FT /note="4"
FT REPEAT 162..183
FT /note="5"
FT REPEAT 184..205
FT /note="6"
FT REPEAT 224..245
FT /note="8"
FT REGION 74..245
FT /note="8 X 22 AA approximate tandem repeats"
FT REGION 152..162
FT /note="LDL and other lipoprotein receptors binding"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT REGION 204..273
FT /note="Lipid-binding and lipoprotein association"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT REGION 261..273
FT /note="Specificity for association with VLDL"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT BINDING 156..159
FT /ligand="heparin"
FT /ligand_id="ChEBI:CHEBI:28304"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT BINDING 219..226
FT /ligand="heparin"
FT /ligand_id="ChEBI:CHEBI:28304"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT MOD_RES 137
FT /note="Methionine sulfoxide"
FT /evidence="ECO:0000250|UniProtKB:P08226"
FT MOD_RES 141
FT /note="Phosphoserine"
FT /evidence="ECO:0000250|UniProtKB:P02649"
SQ SEQUENCE 299 AA; 34079 MW; 4C16EDD3B722BCBD CRC64;
MKVLWAVLVV TLLAGCRADA EPELEAQEPA VWQSGQPWEL ALGRLWDYLR WVQTLSDQVQ
EELLSSQVTQ ELTLLMEDTM KEVKAYKAEL EQELAPMAED TRARLSKELQ AAQARLGADM
EEVRNRLAQY RGEVQAMLGQ SAEELRARLA SHLRKMRKRL LRDAEDLQKR LAVYKAGARE
GAERGVSAIR ERLASLVEQG RLRSALTSQP LRERAQAWGE RLRGRLEEVG GQARDRLDVV
REQMEEVRAK VEEQAEAFQA RLKGWFEPMV EDMRRQWADL IEKVQVAVGA STPAPSQKP
