Abstract:
:Transport of the antifolate cancer drug methotrexate was studied in vesicles isolated from the basolateral membrane of rat liver. Transport of methotrexate by basolateral membrane vesicles (BLMVs) was mostly via uptake into an osmotically active intravesicular space, with some binding (approximately 9%), as shown by initial uptake studies and by varying medium osmolarity with increasing concentrations of sucrose. Methotrexate transport was linear for the first 20 s of incubation. Transport was not affected by imposition of a Na+ gradient across the vesicular membrane. Transport of methotrexate displayed a broad pH optimum: at an intravesicular pH of 7.5, the initial rate of uptake was not significantly different at extravesicular pH values ranging from 5.5 to 7.5, but uptake was less at extravesicular pH of 5.0 or 8.0. Methotrexate transport was saturable: Km = 0.15 +/- 0.05 microM and Vmax = 11.4 +/- 1.1 pmol 10 s-1 mg-1 protein. Methotrexate uptake into BLMVs was not inhibited by 5-methyltetrahydrofolate nor by 5-formyltetrahydrofolate but was weakly inhibited by folic acid in a concentration-dependent manner. Uptake was also inhibited by anion-exchange inhibitor 4,4'-diisothio-cyanostilbene-2,2'-disulfonic acid (DIDS), and by the structurally unrelated anions ATP, ADP, Cl-, SO4(2-), and oxalate2-. Adenosine (no negative charge) had no effect on transport. When vesicles were preloaded with anions (ADP, SO4(2-), oxalate2-) such that an anion gradient existed from the intra- to the extravesicular compartment, and methotrexate uptake was measured, no stimulation of uptake was seen. Methotrexate uptake into rat liver BLMVs was electrogenic as shown by stimulation of the initial rate of uptake by a valinomycin-imposed K+ diffusion potential across the vesicular membrane. These results suggest that methotrexate is transported into the hepatocyte across the basolateral membrane by an electrogenic, multispecific anion carrier system.
journal_name
Arch Biochem Biophysjournal_title
Archives of biochemistry and biophysicsauthors
Horne DW,Reed KAdoi
10.1016/0003-9861(92)90102-3subject
Has Abstractpub_date
1992-10-01 00:00:00pages
121-8issue
1eissn
0003-9861issn
1096-0384pii
0003-9861(92)90102-3journal_volume
298pub_type
杂志文章abstract::The lysosomal cysteine proteinases, cathepsins B, H, and L, were all shown to bind to alpha 2-macroglobulin. The bound enzymes remained active against low-molecular-weight synthetic substrates and bound the active-site-directed inhibitor, benzyloxycarbonyl-125I-Tyr-Ala-diazomethane. Binding of the radiolabeled inhibit...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(89)90495-5
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abstract::Myelin basic protein is known to be released into the circulation following traumatic injuries or demyelination within the central nervous system, resulting in the generation of potentially immunogenic myelin basic protein material. In this investigation we have studied the binding of bovine and human myelin basic pro...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.1998.0902
更新日期:1998-11-15 00:00:00
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journal_title:Archives of biochemistry and biophysics
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更新日期:2004-02-01 00:00:00
abstract::The St-20 and ST-40 cDNAs encode rat liver hydroxysteroid sulfotransferases (HS-ST) that are 90% identical in amino acid sequence but exhibit different substrate preferences for dehydroepiandrosterone (DHEA), androsterone (AD), and cortisol (CS). ST-40 is active for all three substrates, whereas ST-20 is mainly active...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.1997.9979
更新日期:1997-05-15 00:00:00
abstract::New and stimulating results have challenged the concept that cellular senescence might not be synonymous with aging. It is indisputable that during aging, senescent cell accumulation has an impact on organismal health. Nevertheless, senescent cells are now known to display physiological roles during embryonic developm...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章,评审
doi:10.1016/j.abb.2016.04.004
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abstract::The intrinsic fluorescence of potato tuber pyrophosphate:fructose-6-phosphate 1-phosphotransferase (PFP) was used as an indicator of conformational changes due to ligand binding. Binding of the substrates and the allosteric activator fructose-2,6-bisphosphate was quantitatively compared to their respective kinetic eff...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/s0003-9861(03)00157-7
更新日期:2003-06-01 00:00:00
abstract::Calcium-induced changes in protein solubility play a role in a variety of important biological processes including the deposition of bone and dentin and the secretion of milk. The phenomena of salt-induced (calcium) precipitation of proteins (salting-out), and the resolubilization of these proteins at higher salt conc...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(88)90380-3
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abstract::XynA from Erwinia chrysanthemi (EcXyn30A), belonging to glycoside hydrolase family 30 subfamily 8, is specialized for hydrolysis of 4-O-methylglucuronoxylan (GX). Carboxyl group of 4-O-methylglucuronic acid serves as a substrate recognition element interacting ionically with positively charged Arg293 of the enzyme. We...
journal_title:Archives of biochemistry and biophysics
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
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abstract::Dark incubation of envelope vesicles derived from a strain of Halobacterium halobium that lacks bacteriorhodopsin but contains halorhodopsin and a third rhodopsin-like pigment caused a decrease in the flash yield [the amplitude of a transient absorbance change of flash reactive component(s) by flash] of halorhodopsin ...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
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abstract::Phosphatidylserine (PS) is predominantly confined to the inner leaflet of plasma membrane in cells, but it is externalized on the cell surface during apoptosis. This externalized PS is required for effective phagocytosis of apoptotic cells by macrophages. Because PS trans-bilayer asymmetry is not absolute in different...
journal_title:Archives of biochemistry and biophysics
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2015.10.001
更新日期:2015-11-15 00:00:00
abstract::Nitric oxide (.NO) and peroxynitrite (ONOO-) inhibit enzymes that depend on metal cofactors or oxidizable amino acids for activity. Since xanthine oxidase (XO) is a 2(2Fe2S) enzyme having essential sulfhydryl groups linked with Mo-pterin cofactor function, the influence of .NO and ONOO- on purified bovine XO was deter...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.1998.0675
更新日期:1998-07-01 00:00:00
abstract::We have isolated and characterized a human liver glutathione S-transferase Ha1 subunit gene. The gene spans approximately 12 kilobases and comprises seven exons separated by six introns. The transcription initiation site has been determined by primer extension analysis. A TATA box is located 26 nucleotides upstream fr...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(92)90035-u
更新日期:1992-02-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2015.03.015
更新日期:2015-05-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(90)90234-p
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abstract::The Ku autoantigen is a heterodimeric protein of 70- and 83-kDa subunits, endowed with duplex DNA end-binding capacity and DNA helicase activity (Human DNA Helicase II, HDH II). HDH II/Ku is well established as the DNA binding component, the regulatory subunit as well as a substrate for the DNA-dependent protein kinas...
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更新日期:2008-02-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.1999.1403
更新日期:1999-11-01 00:00:00
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更新日期:2005-12-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.1994.1491
更新日期:1994-11-15 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
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更新日期:1986-12-01 00:00:00
abstract::In our previous reports [Z. Long, H. Homma, J.-A. Lee, T. Fukushima, T. Santa, T. Iwatsubo, R. Yamada, K. Imai, FEBS Lett. 434 (1998) 231-235; Z. Long, M. Sekine, M. Adachi, T. Furuchi, K. Imai, N. Nimura, H. Homma, Arch. Biochem. Biophys. 404 (2002) 92-97], we demonstrated for the first time that D-aspartate (D-Asp) ...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2005.12.008
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1006/abbi.2000.1987
更新日期:2000-09-15 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/j.abb.2005.02.022
更新日期:2005-04-15 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(85)90494-1
更新日期:1985-10-01 00:00:00
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journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
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更新日期:1988-11-15 00:00:00
abstract::The expression and activity of the phenobarbital (PB)-inducible P-450 isozymes, P-450b and P-450e, and the major 3-methylcholanthrene (MC)-inducible form, P-450c, were studied in primary cultures of adult rat hepatocytes in T1, Leibovitz L-15 (L-15), and a modification of Waymouth 752/1 (Way) media. P-450 isozymes in ...
journal_title:Archives of biochemistry and biophysics
pub_type: 杂志文章
doi:10.1016/0003-9861(88)90629-7
更新日期:1988-05-15 00:00:00