Gene Ontology annotation through association of InterPro records with GO terms
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara
Electronic Gene Ontology annotations created by ARBA machine learning models
Combined Automated Annotation using Multiple IEA Methods
Selective interaction of megalin with postsynaptic density-95 (PSD-95)-like membrane-associated guanylate kinase (MAGUK) proteins.
-
Yeast interaction cloning and overexpression co-immunoprecipitation identified PSD-95/DLG4 as a megalin cytoplasmic-tail partner.
"Using interaction
cloning in yeast, we identified the membrane-associated guanylate kinase family
member postsynaptic density-95 (PSD-95) as an interaction partner for megalin.
PSD-95 and a truncated version of megalin were co-immunoprecipitated from
HEK-293 cell lysates overexpressing the two proteins, which confirmed the
interaction."
-
The megalin C-terminal PDZ-binding motif interacted with the PSD-95 PDZ2 domain, with selective binding among related MAGUK proteins.
"We found that the interaction between the two proteins is mediated by
the binding of the C-terminus of megalin, which has a type I PSD-95/ Drosophila
discs-large/zona occludens 1 (PDZ)-binding motif, to the PDZ2 domain of PSD-95."
The adaptor protein ARH escorts megalin to and through endosomes.
-
ARH/LDLRAP1 binds the first megalin FXNPXY motif and colocalizes with megalin along clathrin-coated and recycling-endosome routes.
"We found that ARH also binds
to the first FXNPXY motif of megalin in two-hybrid, pull-down and
coimmunoprecipitation assays. ARH colocalizes with megalin in clathrin coated
pits and in recycling endosomes in the Golgi region."
-
ARH increased lactoferrin uptake through megalin minireceptors in polarized canine kidney cells.
"Expression of ARH in Madin-Darby canine kidney cells
expressing megalin mini-receptors enhances megalin-mediated uptake of
125I-lactoferrin, a megalin ligand."
Megalin mediates renal uptake of heavy metal metallothionein complexes.
-
Metallothionein bound megalin but not cubilin in direct surface plasmon resonance assays, with divalent-cation dependence.
"First, MT binds megalin, but not
cubilin, in direct surface plasmon resonance studies. Binding of MT occurs at a
single site with a K(d) approximately 10(-4) and, as with other megalin ligands,
depends on divalent cations."
-
Antibody competition, uptake competition, and colocalization support megalin-mediated metallothionein uptake in rat-derived renal/yolk-sac systems.
"Anti-megalin antisera, but not control sera, displace >90% bound MT from rat
renal brush-border membranes. Megalin ligands including beta(2)-microglobulin
and also recombinant MT fragments compete for uptake by megalin-expressing rat
yolk sac BN-16 cells. Third, megalin and fluorescently labeled MT colocalize in
BN-16 cells, as shown by fluorescent microscopic techniques."
Megalin mediates the transport of leptin across the blood-CSF barrier.
-
Rodent and human analyses supported leptin binding to megalin at choroid-plexus epithelium and transport into brain.
"We have used different immunoassays and lentiviral vectors to analyze
the role of megalin in the transport of leptin in rodents and humans. We
demonstrate that circulating leptin is transported into the brain by binding to
megalin at the choroid plexus epithelium."
-
Reduced megalin expression in aging and Alzheimer-disease contexts correlated with reduced leptin entry, but this is correlative disease evidence.
"Indeed, the downregulation of megalin
expression in physiological and pathological situations such as aging and
Alzheimer's disease was correlated with poor entry of leptin into the brain."
Integral and associated lysosomal membrane proteins.
Large-scale proteomics and phosphoproteomics of urinary exosomes.
Gentamicin binds to the megalin receptor as a competitive inhibitor using the common ligand binding motif of complement type repeats: insight from the nmr structure of the 10th complement type repeat domain alone and in complex with gentamicin.
-
The study solved the NMR structure of human megalin complement repeat 10 and modeled its interaction with gentamicin from NMR titration data.
"To address this gap in our knowledge, we have solved the NMR structure of the 10th complement type repeat of human megalin and investigated its interaction with gentamicin."
-
Gentamicin bound with low affinity through a common acidic LDLR-family ligand-binding motif involving Trp1126 and Asp1129/Asp1131/Asp1133.
"Gentamicin binds to megalin with low affinity and exploits the common ligand binding motif previously described (Jensen, G. A., Andersen, O. M., Bonvin, A. M., Bjerrum-Bohr, I., Etzerodt, M., Thogersen, H. C., O'Shea, C., Poulsen, F. M., and Kragelund, B. B. (2006) J. Mol. Biol. 362, 700–716) utilizing the indole side chain of Trp-1126 and the negatively charged residues Asp-1129, Asp-1131, and Asp-1133."
Structural basis for endosomal trafficking of diverse transmembrane cargos by PX-FERM proteins.
In-depth proteomic analyses of exosomes isolated from expressed prostatic secretions in urine.
Renal uptake of the antiapoptotic protein survivin is mediated by megalin at the apical membrane of the proximal tubule.
-
Human kidney imaging and human primary tubular cells localized survivin with megalin in the proximal-tubule apical region.
"Immunoelectron microscopy also showed
apical localization of survivin in human kidneys. Furthermore, in polarized
human primary tubular cells endogenous as well as external recombinant survivin
is stored in the apical region of the cells. Costaining of survivin and megalin
by immunohistochemistry and immunoelectron microscopy confirmed colocalization."
-
Survivin bound megalin and cubilin by surface plasmon resonance, and megalin-knockout mice lost survivin in urine.
"Finally, by surface plasmon resonance we were able to demonstrate that survivin
binds megalin and cubilin and that megalin knockout mice lose survivin through
the urine."
Establishment and Dysfunction of the Blood-Brain Barrier.
MicroRNA-146a represses LRP2 translation and leads to cell apoptosis in Alzheimer's disease.
-
miR-146a overexpression in SH-SY5Y cells reduced LRP2 expression and Akt activation while increasing caspase-3 and apoptosis.
"Overexpression of miRNA-146a in
SH-SY5Y cells significantly decreased Lrp2 expression, resulting in a reduction
of Akt activation and induction of proapoptotic caspase-3, thereby increasing
cell apoptosis."
-
The proposed Alzheimer-disease contribution is an inference from a cultured neuroblastoma-cell perturbation, not direct patient-tissue causality.
"Thus, specific miRNA-146a regulation may contribute to AD by
downregulating the Lrp2/Akt pathway."
Megalin Is Predominantly Observed in Vesicular Structures in First and Third Trimester Cytotrophoblasts of the Human Placenta.
-
Human first-trimester and term placenta showed predominant LRP2/megalin expression in cytotrophoblasts, with limited syncytiotrophoblast signal.
"By immunohistochemical analyses
of first trimester and term human placenta, we showed that megalin is
predominantly expressed in cytotrophoblasts, the highly proliferative cells in
placenta. Only limited amounts of megalin could be detected in
syncytiotrophoblasts and least in term placenta syncytiotrophoblasts."
-
Placental megalin associated with endolysosomal structures; the observed distribution argued against maternal nutrient uptake as its main placental role.
"Immunocytochemical analyses furthermore showed that placental megalin associates
with structures of the endolysosomal apparatus. Combined, our results clearly
place placental megalin in the context of endocytosis and trafficking of
ligands. However, due to the limited expression of megalin in
syncytiotrophoblasts, especially in term placenta, it appears that the main role
for placental megalin is not to mediate uptake of nutrients from the maternal
bloodstream, as previously proposed."
Architecture of the human interactome defines protein communities and disease networks.
Blood-Brain Barrier: From Physiology to Disease and Back.
Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
Identification of glycoprotein 330 as an endocytic receptor for apolipoprotein J/clusterin.
-
gp330/LRP2 bound human-milk clusterin with high affinity, whereas LRP1 did not bind clusterin in the same assays.
"Solid-phase binding assays confirmed
that gp330 bound to apoJ with high affinity (Kd = 14.2 nM). Similarly, gp330
bound to apoJ transferred to nitrocellulose after SDS-polyacrylamide gel
electrophoresis. LRP, however, showed no binding to apoJ in either type of
assay."
-
Only gp330-expressing cultured cells internalized and degraded radiolabeled clusterin, and uptake was blocked by competitors or gp330 antibodies.
"Only cells that expressed gp330
endocytosed and degraded radiolabeled apoJ."
Megalin-mediated endocytosis of transcobalamin-vitamin-B12 complexes suggests a role of the receptor in vitamin-B12 homeostasis.
-
Rabbit kidney megalin bound transcobalamin-vitamin-B12 with high affinity, whereas LRP1 had no measurable affinity in the same assay.
"Surface plasmon resonance
analysis demonstrated a high-affinity interaction between purified rabbit
megalin and rabbit TC-B12 but no measurable affinity of the vitamin complex for
the homologous alpha 2-macroglobulin receptor (alpha 2MR)/low density
lipoprotein receptor related protein (LRP)."
-
Rat model cells and microperfused proximal tubules internalized TC-B12 in a megalin/RAP-sensitive pathway.
"125I-TC-B12 was efficiently
endocytosed in a RAP-inhibitable manner in megalin-expressing rat yolk sac
carcinoma cells and in vivo microperfused rat proximal tubules."
Interaction of apolipoprotein J-amyloid beta-peptide complex with low density lipoprotein receptor-related protein-2/megalin. A mechanism to prevent pathological accumulation of amyloid beta-peptide.
-
A-beta1-40 did not bind LRP2 alone, but clusterin-A-beta complexes did bind LRP2.
"The
results showed that Abeta alone did not bind directly to LRP-2; however, when
Abeta1-40 was combined with apoJ to form a complex, binding to LRP-2 took place."
-
LRP2-expressing cells internalized and degraded purified clusterin-A-beta complexes in an antibody-sensitive pathway.
"When the cells were provided purified
125I-Abeta1-40-apoJ complex, the complex was internalized and degraded, and both
processes were inhibited with polyclonal LRP-2 antibodies."
Megalin is an endocytic receptor for insulin.
-
Renal microvillar-membrane crosslinking and immunoprecipitation identified megalin as an insulin-binding receptor.
"In this study, an insulin binding site was identified in renal microvillar
membranes by chemical cross-linking procedures. By immunoprecipitation it was
demonstrated that this binding site is megalin, the large multiligand binding
endocytic receptor that is abundantly expressed in clathrin-coated pits on the
apical surface of proximal tubule cells."
-
Megalin internalized insulin into endocytic vesicles and also bound several other low-molecular-weight polypeptides in ligand blots.
"Moreover, using cytochemical
procedures, it was also shown that megalin is able to internalize insulin into
endocytic vesicles."
Mutations in LRP2, which encodes the multiligand receptor megalin, cause Donnai-Barrow and facio-oculo-acoustico-renal syndromes.
-
Pathogenic LRP2 variants were identified in multiple human Donnai-Barrow and facio-oculo-acoustico-renal syndrome families.
"By studying multiplex
families, we mapped this disorder to chromosome 2q23.3-31.1 and identified LRP2
mutations in six families with Donnai-Barrow syndrome and one family with
facio-oculo-acoustico-renal syndrome."
Structures of LRP2 reveal a molecular machine for endocytosis.
-
Cryo-EM structures of mouse-kidney LRP2 at extracellular and endosomal pH showed ligand-receptive and ligand-shedding conformations.
"Here, we report high-resolution cryoelectron
microscopy structures of LRP2 isolated from mouse kidney, at extracellular and
endosomal pH. The structures reveal LRP2 to be a molecular machine that adopts a
conformation for ligand binding at the cell surface and for ligand shedding in
the endosome."
-
LRP2 forms a pH-regulated homodimer whose interfaces change during the endocytic conformational transition.
"LRP2 forms a homodimer, the conformational transformation of which
is governed by pH-sensitive sites at both homodimer and intra-protomer
interfaces."
-
A subset of human deleterious missense variants was structurally consistent with impaired homodimer assembly.
"A subset of LRP2 deleterious missense variants in humans appears to
impair homodimer assembly."
Vitamin D (calciferol) metabolism
LRPs transport extracellular CR:atREs:HSPG:apoE to cytosol
LRP2-mediated uptake of extracellular CUBN:GC:25(OH)D
F- and N- BAR domain proteins bind the clathrin-coated pit
CLASP proteins and cargo are recruited to the nascent clathrin-coated pit
Clathrin recruits PIK3C2A
Clathrin-associated PIK3C2A phosphorylates PI(4)P to PI(3,4)P2
SNX9 recruits components of the actin polymerizing machinery
BAR domain proteins recruit dynamin
SYNJ hydrolyze PI(4,5)P2 to PI(4)P
Endophilins recruit synaptojanins to the clathrin-coated pit
HSPA8-mediated ATP hydrolysis promotes vesicle uncoating
Clathrin recruits auxilins to the clathrin-coated vesicle
Auxilin recruits HSPA8:ATP to the clathrin-coated vesicle
Dynamin-mediated GTP hydrolysis promotes vesicle scission
Dissociation of clathrin-associated proteins
Dissociation of AAK1 and dephosphorylation of AP-2 mu2
RAB5 and GAPVD1 bind AP-2
Retinoid metabolism and transport
Transport of RCbl within the body
LRP2-mediated TCN2:RCbl uptake and delivery to lysosome
LRP2 binds extracellular TCN2:RCbl
UniProtKB/Swiss-Prot record for human LRP2 (P98164)