Search results for "Peptide transport"
showing 5 items of 5 documents
Induction of Human P-Glycoprotein in Caco-2 cells: Development of a Highly Sensitive Assay System for P-Glycoprotein-Mediated Drug Transport
2006
The aim of this work is to develop a highly sensitive assay system for P-gp-mediated transport by using two methods, induction of P-gp and short-term culture of Caco-2 cells. To induce P-gp in Caco-2 cells, cells were cultured in vinblastine-containing medium. The mRNA level of P-gp was approximately 7-fold higher in Caco-2 cells cultured with vinblastine (P-gp-induced Caco-2 cells) than in control cells. Western blot analysis showed a significant increase in P-gp expression. After cell differentiation, the mRNA level of P-gp was downregulated, however, P-gp-induced Caco-2 cells still possessed a 5.6-fold higher mRNA level of P-gp compared to control cells. Polarized transport of substrate …
Identification of sequences in the human peptide transporter subunit TAP1 required for transporter associated with antigen processing (TAP) function
2001
The heterodimeric peptide transporter associated with antigen processing (TAP) consisting of the subunits TAP1 and TAP2 mediates the transport of cytosolic peptides into the lumen of the endoplasmic reticulum (ER). In order to accurately define domains required for peptide transporter function, a molecular approach based on the construction of a panel of human TAP1 mutants and their expression in TAP1(-/-) cells was employed. The characteristics and biological activity of the various TAP1 mutants were determined, and compared to that of wild-type TAP1 and TAP1(-/-) control cells. All mutant TAP1 proteins were localized in the ER and were capable of forming complexes with the TAP2 subunit. H…
Differential cystine and dibasic amino acid handling after loss of function of the amino acid transporter b0,+ AT (Slc7a9) in mice
2013
Cystinuria is an autosomal recessive disease caused by mutations in SLC3A1 ( rBAT) and SLC7A9 ( b 0,+ AT). Gene targeting of the catalytic subunit ( Slc7a9) in mice leads to excessive excretion of cystine, lysine, arginine, and ornithine. Here, we studied this non-type I cystinuria mouse model using gene expression analysis, Western blotting, clearance, and brush-border membrane vesicle (BBMV) uptake experiments to further characterize the renal and intestinal consequences of losing Slc7a9 function. The electrogenic and BBMV flux studies in the intestine suggested that arginine and ornithine are transported via other routes apart from system b0,+. No remarkable gene expression changes were…
Functional cysteine-less subunits of the transporter associated with antigen processing (TAP1 and TAP2) by de novo gene assembly
2002
AbstractWithin the adaptive immune system the transporter associated with antigen processing (TAP) plays a pivotal role in loading of peptides onto major histocompatibility (MHC) class I molecules. As a central tool to investigate the structure and function of the TAP complex, we created cysteine-less human TAP subunits by de novo gene synthesis, replacing all 19 cysteines in TAP1 and TAP2. After expression in TAP-deficient human fibroblasts, cysteine-less TAP1 and TAP2 are functional with respect to adenosine triphosphate (ATP)-dependent peptide transport and inhibition by ICP47 from herpes simplex virus. Cysteine-less TAP1 and TAP2 restore maturation and intracellular trafficking of MHC c…
Regulated Proteolysis of RAGE and AβPP as Possible Link Between Type 2 Diabetes Mellitus and Alzheimer's Disease
2009
Epidemiological studies have linked type 2 diabetes mellitus (T2DM) with an increased risk of developing Alzheimer's disease (AD). In T2DM, the elevated blood glucose level promotes formation of advanced glycation end products (AGEs). The receptor for AGEs (RAGE) is a type I membrane-protein and is also able to import amyloid-beta (Abeta) from the blood across the blood-brain-barrier into the brain. Oligomeric Abeta peptides disturb synaptic function in the brain and are believed to contribute to the development of AD. Abeta peptides are released from the amyloid-beta protein precursor (AbetaPP) after sequential proteolysis by beta- and gamma-secretases but alpha-secretase-mediated cleavage…