Complete cloning and sequencing of rat gp330/"megalin," a distinctive member of the low density lipoprotein receptor gene family.

Saito, Akihiko; Pietromonaco, Salvatore F.; Loo, Alvin Kwor-Chieh; Farquhar, Marilyn G.

doi:10.1073/pnas.91.21.9725

Cited by 524 publications

(384 citation statements)

References 36 publications

(39 reference statements)

Supporting

Mentioning

373

Contrasting

Unclassified

Order By: Relevance

“…2). Megalin (or LRP2) is 600 kDa protein specifically expressed on the apical surface of absorptive epithelia (Saito et al, 1994). Prominent sites of expression in the adult organism are the proximal tubules in the kidney, the uterine epithelium, the epididymis, the mammary gland, as well as the ependyma in the brain ventricles (Zheng et al, 1994).…”

Section: Megalin a Receptor For Cellular Uptake Of Vitamin D Metabolmentioning

confidence: 99%

Cellular uptake of steroid carrier proteins—Mechanisms and implications

Willnow

Nykjaer

2010

Molecular and Cellular Endocrinology

View full text Add to dashboard Cite

Steroid hormones are believed to enter cells solely by free diffusion through the plasma membrane. However, recent studies suggest the existence of cellular uptake pathways for carrier-bound steroids. Similar to the clearance of cholesterol via lipoproteins, these pathways involve the recognition of carrier proteins by endocytic receptors on the surface of target cells, followed by internalization and cellular delivery of the bound sterols. Here, we discuss the emerging concept that steroid hormones can selectively enter steroidogenic tissues by receptor-mediated endocytosis; and we discuss the implications of these uptake pathways for steroid hormone metabolism and action in vivo.

show abstract

Section: Megalin a Receptor For Cellular Uptake Of Vitamin D Metabolmentioning

confidence: 99%

Cellular uptake of steroid carrier proteins—Mechanisms and implications

Willnow

Nykjaer

2010

Molecular and Cellular Endocrinology

View full text Add to dashboard Cite

show abstract

“…AHN is induced by immunization with a crude fraction of renal cortex, termed Fx1A (1, 3), or its major autoantigenic constituent, a glycoprotein variously called gp600 (4,5), gp330 (6), or megalin (7). The rat disease reproduces the morphological, immunohistological, ultrastructural, and clinical features of the human syndrome, including the characteristic nephrotic lesion and elevated proteinuria.…”

Section: A Ctive Heymann Nephritis (Ahn)mentioning

confidence: 99%

“…The primary sequence of megalin identifies it as a member of the LDL receptor family (7). The size, structural complexity, and extensive glycosylation of the intact molecule present serious challenges for an analysis of its immunogenic and nephritogenic determinants.…”

Section: A Ctive Heymann Nephritis (Ahn)mentioning

confidence: 99%

Conformation and Glycosylation of a Megalin Fragment Correlate with Nephritogenicity in Heymann Nephritis

Tramontano

Makker

2004

The Journal of Immunology

View full text Add to dashboard Cite

Active Heymann nephritis (AHN), a rat model of autoimmune glomerulonephritis, is induced by immunization with autologous megalin, a 600-kDa cell surface glycoprotein isolated from crude renal extracts. Recombinant proteins containing a 563-residue N-terminal sequence of megalin were obtained from Escherichia coli and baculovirus-insect cell expression systems. Rats immunized with the soluble, secreted protein encoded by a baculovirus construct elicited high titer anti-megalin autoantibodies and developed glomerular immune deposits and elevated proteinuria consistent with AHN. Rats treated with the bacterial or nonsecreted insect cell proteins produced a milder anti-megalin response and did not develop the disease. Nephritogenicity appeared to correlate with conformational or other structural features of native megalin. All three recombinant proteins were reactive in Western blots with rabbit anti-megalin antiserum, whereas the insect cell-derived proteins reacted preferentially in Western blot and ELISA with anti-megalin autoantibodies from rats with AHN induced by native megalin. Only the secreted insect cell product was stained in a lectin blot, suggesting its specific glycosylation. These observations provide evidence that a megalin N-terminal domain includes B and T cell epitopes sufficient for a pathogenic autoimmune response and that a native-like conformation and glycosylation are essential for the induction of disease. The importance of conformational B cell epitopes for pathogenic autoantibodies recapitulates observations made in other models of organ-specific autoimmune disease. Glycosidic modifications could influence the presentation of either B or T cell epitopes in AHN, consistent with emerging evidence of the role of post-translational modifications in pathogenic autoimmune responses.

show abstract

“…LRP is a member of the LDL receptor family, which includes the LDL receptor (13), the VLDL receptor (14), gp330/megalin (15), and a newly described apolipoprotein E receptor 2 (16). A 39-kDa protein, termed the receptor-associated protein (RAP) (17), binds to several members of the LDL receptor family (18 -20) and blocks their ligand binding capacity.…”

mentioning

confidence: 99%

Cellular Internalization and Degradation of Thrombospondin-1 Is Mediated by the Amino-terminal Heparin Binding Domain (HBD)

Mikhailenko

Krylov²,

Argraves

et al. 1997

Journal of Biological Chemistry

107

View full text Add to dashboard Cite

Thrombospondin-1 (TSP-1) is a large modular trimeric protein that has been proposed to play a diverse role in biological processes. Newly synthesized TSP-1 either is incorporated into the matrix or binds to the cell surface where it is rapidly internalized and degraded. TSP-1 catabolism is mediated by the low density lipoprotein receptor-related protein (LRP), a large endocytic receptor that is a member of the low density lipoprotein receptor family. Using adenovirus-mediated gene transfer experiments, we demonstrate that the very low density lipoprotein receptor can also bind and internalize TSP-1. An objective of the current investigation was to identify the portion of TSP-1 that binds to these endocytic receptors. The current studies found that the amino-terminal heparin binding domain (HBD, residues 1-214) of mouse TSP-1, when prepared as a fusion protein with glutathione S-transferase (GST), bound to purified LRP with an apparent K D ranging from 10 to 25 nM. Recombinant HBD (rHBD) purified following proteolytic cleavage of GST-HBD, also bound to purified LRP, but with an apparent K D of 830 nM. The difference in affinity was attributed to the fact that GST-HBD exists in solution as a dimer, whereas rHBD is a monomer. Like TSP-1, 125 I-labeled GST-HBD or 125 I-labeled rHBD were internalized and degraded by wild type fibroblasts that express LRP, but not by fibroblasts that are genetically deficient in LRP. The catabolism of both 125 I-labeled GST-HBD and rHBD in wild type fibroblast was blocked by the 39-kDa receptor-associated protein, an inhibitor of LRP function. GST-HBD and rHBD both completely blocked catabolism of 125 I-labeled TSP-1 in a dose-dependent manner, as did antibodies prepared against the HBD. Taken together, these data provide compelling evidence that the amino-terminal domain of TSP-1 binds to LRP and thus the recognition determinants on TSP-1 for both LRP and for cell surface proteoglycans reside within the same TSP-1 domain. Further, high affinity binding of TSP-1 to LRP likely results from the trimeric structure of TSP-1.Thrombospondin-1 (TSP-1) 1 is a large glycoprotein composed of three identical subunits, which are covalently linked by interchain disulfide bonds. This molecule is a part of a family of proteins that currently consists of five members (for reviews, see Refs. 1-3). Each subunit of TSP-1 is composed of an aminoterminal heparin binding domain, a type I procollagen homology region, three properdin repeats, three epidermal growth factor-like repeats, seven calcium binding repeats, and a carboxyl-terminal domain (4). TSP-1 has been proposed to play a diverse role in numerous biological processes; these include embryonic development (5), angiogenesis (6), and hemostasis (7,8). The ability of TSP-1 to influence these biological processes has been attributed to its capacity to bind to matrix proteins, proteinases, growth factors, and cell surface receptors.Given that TSP-1 appears to influence a large number of biological processes, it is not surprising that levels of TSP-1 ar...

show abstract

Complete cloning and sequencing of rat gp330/"megalin," a distinctive member of the low density lipoprotein receptor gene family.

Cited by 524 publications

References 36 publications

Cellular uptake of steroid carrier proteins—Mechanisms and implications

Cellular uptake of steroid carrier proteins—Mechanisms and implications

Conformation and Glycosylation of a Megalin Fragment Correlate with Nephritogenicity in Heymann Nephritis

Cellular Internalization and Degradation of Thrombospondin-1 Is Mediated by the Amino-terminal Heparin Binding Domain (HBD)

Contact Info

Product

Resources

About