Cholesterol and phospholipids are essential to the body, but an excess of cholesterol or lipids is toxic a risk factor for arteriosclerosis. ABCG1, one half-type ABC proteins, thought be involved in homeostasis. To explore role ABCG1 homeostasis, we examined its subcellular localization function. ABCG1-K120M, WalkerA lysine mutant, were localized plasma membrane HEK293 cells stably expressing formed homodimer. A stable transformant exhibited efflux choline presence BSA, was enhanced by HDL,...

Apolipoprotein-mediated release of cellular cholesterol and phospholipids was induced in HEK293 cells by expressing human ATP-binding cassette transporter A7 (ABCA7) ABC A1 (ABCA1) proteins, whether transient or stable, to generate cholesterol-rich high density lipoprotein (HDL). Green fluorescent protein (GFP) attached at their C termini did not influence the lipid reactions. Transfected ABCA7-GFP apolipoprotein-mediated assembly cholesterol-containing HDL also L929 cells, which otherwise...

The ATP-sensitive potassium (K ATP ) channels in pancreatic β cells are critical the regulation of glucose-induced insulin secretion. Although electrophysiological studies provide clues to complex control K by ATP, MgADP, and pharmacological agents, molecular mechanism -channel remains unclear. channel is a heterooligomeric SUR1 subunits ATP-binding-cassette superfamily with two nucleotide-binding folds (NBF1 NBF2) pore-forming Kir6.2 subunits. Here, we report that MgATP but not Mg salt...

ATP-sensitive potassium (KATP) channels, composed of sulfonylurea receptor (SURx) and Kir6.x, play important roles by linking cellular metabolic state to membrane potential in various tissues. Pancreatic, cardiac, vascular smooth muscle KATP which consist different subtypes SURx, differ their responses state. To explore the possibility that interactions SURx with nucleotides cause differential regulation we analyzed properties nucleotide-binding folds (NBFs) SUR1, SUR2A, SUR2B. crude...

ABCA1 mediates release of cellular cholesterol and phospholipid to form high density lipoprotein (HDL). The three different mutants in the first extracellular domain human associated with Tangier disease, R587W, W590S, Q597R, were examined for their subcellular localization function by using ABCA1-GFP fusion protein stably expressed HEK293 cells. was fully functional apoA-I-mediated HDL assembly. Immunostaining confocal microscopic analyses demonstrated that mainly localized plasma membrane...

MDR1 (multidrug resistance 1)/P-glycoprotein is an ATP-driven transporter which excretes a wide variety of structurally unrelated hydrophobic compounds from cells. It suggested that drugs bind to directly the lipid bilayer and cholesterol in also interacts with MDR1. However, effects on drug–MDR1 interactions are still unclear. To examine these effects, human was expressed insect cells purified. The purified protein reconstituted proteoliposomes containing various concentrations enzymatic...

ABCA1 (ATP-binding cassette transporter A1) mediates the release of cellular cholesterol and phospholipid to form high density lipoprotein. Functions are highly regulated at transcriptional post-transcriptional levels, synthesized protein turns over rapidly with a half-life 1–2 h. To examine whether functions modulated by associated proteins, yeast two-hybrid library was screened C-terminal 120 amino acids ABCA1. Two PDZ (PSD95-Discs large-ZO1) α1-syntrophin Lin7, were found interact...

ATP-sensitive potassium channels are under complex regulation by intracellular ATP and ADP. The potentiating effect of MgADP is conferred the sulfonylurea receptor subunit channel, SUR, whereas inhibitory appears to be mediated via pore-forming subunit, Kir6.2. We determined whether directly interacts with a binding site on Kir6.2 mediate channel inhibition analyzing photoaffinity analog (8-azido-[γ-32P]ATP) membranes from COS-7 cells transiently expressing demonstrate that can labeled...

ATP-binding cassette protein A1 (ABCA1) plays a major role in cholesterol homeostasis and high density lipoprotein metabolism. Apolipoprotein A-I binds to ABCA1 cellular phospholipids, mainly phosphatidylcholine, are loaded onto apoA-I form pre-β (HDL). It is proposed that translocates phospholipids directly or indirectly HDL. To explore the mechanism of ABCA1-mediated HDL formation, we expressed human insect Sf9 cells purified it. Trypsin limited-digestion detergent-soluble suggested it...

Abstract Human ABCB4 (multidrug resistance [MDR]3 P-glycoprotein) is expressed in the canalicular membrane of hepatocyte. has been shown to be required for phosphatidylcholine (PC) secretion into bile and translocate PC across plasma membrane. To further investigate function ABCB4, we established a cell line stably expressing (human embryonic kidney [HEK]/ABCB4). The efflux phospholipids from HEK/ABCB4 cells was remarkably increased by addition taurocholate. In addition, cholesterol also...

Pancreatic beta cell ATP-sensitive potassium (K(ATP)) channels regulate glucose-induced insulin secretion. The activity of the K(ATP) channel, composed SUR1 and Kir6.2 subunits, is regulated by intracellular ATP ADP, but molecular mechanism not clear. To distinguish binding properties two nucleotide-binding folds (NBFs) SUR1, we prepared antibodies against NBF1 NBF2, tryptic fragment was immunoprecipitated after photoaffinity labeling with 8-azido-[(32)P]ATP. 35-kDa strongly labeled 5 microM...

Multidrug resistance protein 1 (MRP1) and P-glycoprotein, which are ATP-dependent multidrug efflux pumps involved in of tumor cells, members the ATP binding cassette proteins contain two nucleotide-binding folds (NBFs). P-glycoprotein hydrolyzes at both NBFs, vanadate-induced nucleotide trapping occurs NBFs. We examined MRP1 stably expressed KB cell membrane by using 8-azido-[α-³²P]ATP. Vanadate-induced was found to be stimulated reduced glutathione, glutathione disulfide,...

It is controversial whether the dental resinous materials containing 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl] propane (BisGMA), which synthesized from estrogenic compound bisphenol A (BPA), include unreacted BPA and/or can mimic effects of natural steroid hormones. In present study, activities 3 fissure sealants and 5 adhesive resins, were all unpolymerized, determined by means a reporter gene assay, relevance components to estrogenicity was investigated. Two commercially...

Cholesterol is an essential component of eukaryotic cells; at the same time, however, hyperaccumulation cholesterol harmful. Therefore, ABCA1 gene, product which mediates secretion cholesterol, highly regulated both transcriptional and post-transcriptional levels. The transcription by intracellular oxysterol concentration via nuclear liver X receptor (LXR)/retinoid (RXR); once synthesized, protein turns over rapidly with a half-life 1-2 h. Here, we show that LXRbeta/RXR complex binds...

ABCG1, one of the half-type ATP binding cassette (ABC) proteins, mediates efflux cholesterol to HDL and functions in reverse transport from peripheral cells liver. We have shown that ABCG1 not only but also sphingomyelin (SM) phosphatidylcholine. Because SM preferentially associates with cholesterol, we examined whether it plays an important role ABCG1-mediated cholesterol. The mediated by was reduced a mutant CHO-K1 cell line, LY-A, which cellular level is because mutation ceramide transfer...

ATP binding cassette protein A1 (ABCA1) plays a major role in cholesterol homeostasis and high density lipoprotein (HDL) metabolism. It is proposed that ABCA1 reorganizes the plasma membrane generates more loosely packed domains facilitate apoA-I-dependent efflux. In this study, we examined effects of cellular sphingomyelin level on HDL formation by using Chinese hamster ovary-K1 mutant cell line, LY-A, which has missense mutation ceramide transfer CERT. When LY-A cells were cultured...

ATP-binding cassette protein G1 (ABCG1) is important for the formation of HDL. However, biochemical properties ABCG1 have not been reported, and mechanism how involved in HDL remains unclear. We established a procedure to express purify human using suspension-adapted cell FreeStyle293-F. ABCG1, fused at C terminus with green fluorescent Flag-peptide, was solubilized n-dodecyl-β-D-maltoside purified via single round Flag-M2 antibody affinity chromatography. The reconstituted liposome various...

ATP-binding cassette G1 (ABCG1) and ABCG4, expressed in neurons glia the central nervous system, mediate cholesterol efflux to lipid acceptors. The relationship between level system Alzheimer’s disease has been reported. In this study, we examined effects of ABCG1 ABCG4 on amyloid precursor protein (APP) processing, product which, β (Aβ), is involved pathogenesis disease. Expression or human embryonic kidney 293 cells that stably Swedish-type mutant APP increased cellular cell surface...

ATP-binding cassette A1 (ABCA1), ABCG1, and ABCG4 are lipid transporters that mediate the efflux of cholesterol from cells. To analyze characteristics these transporters, we examined compared their distributions activity on plasma membrane. The mediated by ABCA1 but not ABCG4, was affected a reduction cellular sphingomyelin levels. Detergent solubility gradient density ultracentrifugation assays indicated ABCA1, were distributed to domains solubilized Triton X-100 Brij 96, resistant...

Abstract Composite films of polyacrylonitrile (PAN) and multiwalled carbon nanotubes (MWNTs) have been prepared by gelation/crystallization from solution. The contents MWNTs were 5–10 wt.‐%, measured against PAN. electrical mechanical properties studied in comparison with those the homopolymer PAN same method. Furthermore, stabilization carbonization carried out using drawn PAN–MWNTs as a new precursor to prepare cross‐sectional area much larger than that commercial fiber (>...