Proximal tubular epithelial cells preferentially endocytose covalently‐modified albumin compared to native albumin
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ABSTRACT Aim Albumin can be covalently modified at surface lysine residues and thus the circulation contains a mixture of native albumin (i.e. not modified) and albumin with varying degrees of modification. Uptake and lysosomal degradation of glomerular filtered albumin by proximal tubular cells via the megalin scavenger receptor is considered an important mechanism to limit albumin loss in the urine. However, whether this is a general mechanism of tubular uptake of albumin or if this is restricted to modified albumin is unknown. To address this question, we investigated the uptake of modified versus native albumin by proximal tubular cells. Methods A well‐characterized proximal tubular cell model of albumin uptake was used to compare the uptake of modified albumin (covalent labelling of lysine residues with fluorescent probes) to that of native recombinant human albumin (rHA) labelled with 14 C during protein synthesis ( 14 C‐rHA). Results Opossum kidney (OK) cells showed significant uptake of fluorescence‐labelled albumin via an endocytosis mechanism. This uptake was inhibited by an equimolar ratio of different types of covalently modified albumin; however, purified bovine serum albumin and rHA failed to compete with the uptake of fluorescence‐labelled albumin. In contrast, OK cells failed to endocytose native 14 C‐rHA despite efficiently endocytosing covalently modified rHA. Conclusion Our studies show that OK cells preferentially endocytose covalently‐modified albumin compared to native albumin. This apparent selectivity of the megalin scavenger receptor complex suggests a specific role for this pathway in the removal of modified albumin from the circulation.Keywords:
Scavenger Receptor
Serum Albumin
Bovine serum albumin
Bovine serum albumin
Serum Albumin
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The interaction of Neodymium ions (Ⅲ) with bovine serum albumin(BSA) in different pH range has been investigated by UV spectrometry in microemulsion conditiin. And solid polymer of Nd(III) with bovine serum albumin(BSA) has been prepared, the IR spectrum has measured. It was probed that the position of the interaction of Nd(Ⅲ) with bovine serum albumin(BSA) in mircroemulsion condition.
Bovine serum albumin
Microemulsion
Serum Albumin
Neodymium
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Delayed type hypersensitivity (DTH) to bovine serum albumin (BSA) and to lipid-conjugated BSA were studied comparatively. Unlike the case of BSA with which no DTH can be detected with native antigen, injection of butyric-conjugated BSA (Bu-BSA) in sensitized mice provokes a typical DTH for an early and limited period. Alum-precipitated Bu-BSA (Al-Bu-BSA) provokes from the beginning a stronger DTH which persists a much longer period.
Bovine serum albumin
Serum Albumin
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The association equilibria for complex formation between serum albumin (bovine, rat) and the optical isomers of methamphetamine (MAMP) was determined using an ultrafiltration method. It was found that serum albumin/d-MAMP and serum albumin/l-MAMP complexes had distinctly different Scatchard plots with bovine and rat albumin. The binding parameters of each association equilibrium were estimated from the Scatchard plots by Rosenthal's graphic method. This distinguished two kinds of specific binding sites in terms of the association equilibrium between bovine serum albumin and d-MAMP, and one binding site for rat serum albumin and d-MAMP. One specific binding site was found between serum albumin and l-MAMP in both bovine and rat. Molar ellipticities, [θ], of peaks were decreased in the CD spectra of the complexes formed between bovine serum albumin and d-MAMP or l-MAMP when compared with the CD spectrum of bovine serum albumin alone. However, no difference in [θ] was found between the CD spectra of the enantiomers of MAMP in the measured wavelength range. The non-specific binding site was distinct from the specific binding site and resulting from altered tertiary structure of the albumin molecule. Chirality 10:742–746, 1998. © 1998 Wiley-Liss, Inc.
Methamphetamine
Association (psychology)
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Bovine serum albumin
Serum Albumin
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The association equilibria for complex formation between serum albumin (bovine, rat) and the optical isomers of methamphetamine (MAMP) was determined using an ultrafiltration method. It was found that serum albumin/d-MAMP and serum albumin/l-MAMP complexes had distinctly different Scatchard plots with bovine and rat albumin. The binding parameters of each association equilibrium were estimated from the Scatchard plots by Rosenthal's graphic method. This distinguished two kinds of specific binding sites in terms of the association equilibrium between bovine serum albumin and d-MAMP, and one binding site for rat serum albumin and d-MAMP. One specific binding site was found between serum albumin and l-MAMP in both bovine and rat. Molar ellipticities, [θ], of peaks were decreased in the CD spectra of the complexes formed between bovine serum albumin and d-MAMP or l-MAMP when compared with the CD spectrum of bovine serum albumin alone. However, no difference in [θ] was found between the CD spectra of the enantiomers of MAMP in the measured wavelength range. The non-specific binding site was distinct from the specific binding site and resulting from altered tertiary structure of the albumin molecule. Chirality 10:742–746, 1998. © 1998 Wiley-Liss, Inc.
Bovine serum albumin
Serum Albumin
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Bovine serum albumin (BSA) has a wide range of physiological functions involving the binding, transportation, and delivery of fatty acids, porphyrins, bilirubin, steroids, etc. In the present study, we prepared a small squaraine dye (SD), which can selectively detect BSA using fluorescence lifetime imaging microscopy (FLIM), to monitor the endocytosis of BSA in live cultured cells in real time. This approach revealed that BSA uptake is concentration-dependent in living cells. Furthermore, we used paclitaxel (PTX), a chemotherapeutic drug, to influence the endocytosis of BSA in living cells. The results demonstrated that the endocytic rate was clearly reduced after pretreatment with 0.4 µM PTX for 2 h. The present study demonstrates the potential value of using the fluorescence lifetime of SD to detect BSA concentration and study the physiological mechanism of chemotherapeutic drugs.
Bovine serum albumin
Serum Albumin
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Bovine serum albumin
Serum Albumin
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