APOE_SAISC
ID APOE_SAISC Reviewed; 107 AA.
AC Q28995;
DT 15-DEC-1998, integrated into UniProtKB/Swiss-Prot.
DT 01-NOV-1996, sequence version 1.
DT 03-AUG-2022, entry version 82.
DE RecName: Full=Apolipoprotein E;
DE Short=Apo-E;
DE Flags: Fragment;
GN Name=APOE;
OS Saimiri sciureus (Common squirrel monkey).
OC Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC Eutheria; Euarchontoglires; Primates; Haplorrhini; Platyrrhini; Cebidae;
OC Saimiriinae; Saimiri.
OX NCBI_TaxID=9521;
RN [1]
RP NUCLEOTIDE SEQUENCE [MRNA].
RX PubMed=8635577; DOI=10.1016/0014-5793(95)01491-8;
RA Morelli L., Wei L., Amorim A., McDermid J., Abee C.R., Frangione B.,
RA Walker L.C., Levy E.;
RT "Cerebrovascular amyloidosis in squirrel monkeys and rhesus monkeys:
RT apolipoprotein E genotype.";
RL FEBS Lett. 379:132-134(1996).
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; U52029; AAC50442.1; -; mRNA.
DR AlphaFoldDB; Q28995; -.
DR SMR; Q28995; -.
DR GO; GO:0042627; C:chylomicron; IEA:UniProtKB-KW.
DR GO; GO:0031012; C:extracellular matrix; ISS:UniProtKB.
DR GO; GO:0005615; C:extracellular space; ISS:UniProtKB.
DR GO; GO:0034364; C:high-density lipoprotein particle; ISS:UniProtKB.
DR GO; GO:0034363; C:intermediate-density lipoprotein particle; ISS:UniProtKB.
DR GO; GO:0034362; C:low-density lipoprotein particle; ISS:UniProtKB.
DR GO; GO:0034361; C:very-low-density lipoprotein particle; ISS:UniProtKB.
DR GO; GO:0043395; F:heparan sulfate proteoglycan binding; ISS:UniProtKB.
DR GO; GO:0008201; F:heparin binding; ISS:UniProtKB.
DR GO; GO:0042802; F:identical protein binding; ISS:UniProtKB.
DR GO; GO:0008289; F:lipid binding; IEA:UniProtKB-KW.
DR GO; GO:0050750; F:low-density lipoprotein particle receptor binding; ISS:UniProtKB.
DR GO; GO:0033344; P:cholesterol efflux; ISS:UniProtKB.
DR GO; GO:0034382; P:chylomicron remnant clearance; ISS:UniProtKB.
DR GO; GO:0034380; P:high-density lipoprotein particle assembly; ISS:UniProtKB.
DR GO; GO:0071831; P:intermediate-density lipoprotein particle clearance; ISS:UniProtKB.
DR GO; GO:0042158; P:lipoprotein biosynthetic process; ISS:UniProtKB.
DR GO; GO:1905907; P:negative regulation of amyloid fibril formation; ISS:UniProtKB.
DR GO; GO:0031175; P:neuron projection development; ISS:UniProtKB.
DR GO; GO:1900223; P:positive regulation of amyloid-beta clearance; ISS:UniProtKB.
DR GO; GO:0071830; P:triglyceride-rich lipoprotein particle clearance; ISS:UniProtKB.
DR GO; GO:0034447; P:very-low-density lipoprotein particle clearance; ISS:UniProtKB.
DR InterPro; IPR000074; ApoA_E.
DR Pfam; PF01442; Apolipoprotein; 1.
PE 2: Evidence at transcript level;
KW Chylomicron; Extracellular matrix; HDL; Heparin-binding; Lipid transport;
KW Lipid-binding; Oxidation; Phosphoprotein; Repeat; Secreted; Transport;
KW VLDL.
FT CHAIN <1..>107
FT /note="Apolipoprotein E"
FT /id="PRO_0000191638"
FT REPEAT 11..32
FT /note="1"
FT REPEAT 33..54
FT /note="2"
FT REPEAT 55..76
FT /note="3"
FT REPEAT 77..98
FT /note="4"
FT REPEAT 99..>107
FT /note="5"
FT REGION 11..>107
FT /note="5 X 22 AA approximate tandem repeats"
FT REGION 89..99
FT /note="LDL and other lipoprotein receptors binding"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT BINDING 93..96
FT /ligand="heparin"
FT /ligand_id="ChEBI:CHEBI:28304"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT MOD_RES 74
FT /note="Methionine sulfoxide"
FT /evidence="ECO:0000250|UniProtKB:P08226"
FT MOD_RES 78
FT /note="Phosphoserine"
FT /evidence="ECO:0000250|UniProtKB:P02649"
FT NON_TER 1
FT NON_TER 107
SQ SEQUENCE 107 AA; 12328 MW; FF88CED47BD18F7C CRC64;
LSSQVTQELT ALMDETMKEL KAYKSELEEQ LSPVAEETRA RLSKELQAAQ ARLGADMEDV
RSRLAQYRSE VQAMLGQSTD ELRARLASHL RKLRKRLLRD VDDLQKR
