Approaches used to examine the mechanism and regulation of hexose transport in rat myoblasts

1986 ◽  
Vol 64 (11) ◽  
pp. 1081-1091 ◽  
Author(s):  
Tony D'Amore ◽  
Theodore C. Y. Lo
Keyword(s):  
Transport System ◽  
Transport Systems ◽  
Facilitated Diffusion ◽  
Hexose Transport ◽  
Plasma Membrane Vesicles ◽  
Diffusion Type ◽  
High Affinity ◽  
Isolation And Characterization ◽  
Transport Mutants

This review discusses some of the approaches and general criteria that we have used to examine the properties of the hexose transport system in undifferentiated L6 rat myoblasts. These approaches include studying the kinetics of hexose transport in whole cells and plasma membrane vesicles, the effects of various inhibitors on hexose transport, the isolation and characterization of hexose transport mutants, and the use of cytochalasin B (CB) to identify the transport component(s). Transport kinetics indicated that two transport systems are present in these cells. 2-Deoxy-D-glucose is transported primarily by the high affinity system, whereas 3-O-methyl-D-glucose is transported by the low affinity system. Furthermore, these two transport systems are inactivated to different extents by CB. CB has a higher binding affinity for the low affinity hexose transport system. The inhibitory effect of various hexose analogues also revealed the presence of two hexose transport systems. The effects of various ionophores and energy uncouplers on hexose transport suggest that the high affinity system is an active transport process, whereas the low affinity system is of the facilitated diffusion type. The high affinity system is also sensitive to sulfhydryl reagents, whereas the low affinity system is not. Further evidence for the presence of two transport systems comes from the characterization of hexose transport mutants. Two of the mutants isolated are shown to be defective in the high affinity transport system, but not in the low affinity transport system. These mutants are also defective in the CB low affinity binding site. Based on our results a tentative working model for hexose transport in L6 rat myoblasts is presented.

Isolation and characterization of hexose transport mutants in L6 rat myoblasts

1986 ◽  
Vol 126 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Tony D'Amore ◽  
Vincent Duronio ◽  
Matthias O. Cheung ◽  
Theodore C. Y. Lo
Keyword(s):  
Hexose Transport ◽  
Isolation And Characterization ◽  
Transport Mutants

scholarly journals Cytochalasin B as a probe for the two hexose-transport systems in rat L6 myoblasts

1988 ◽  
Vol 251 (1) ◽  
pp. 63-72 ◽  
Author(s):  
S R Chen ◽  
T C Y Lo
Keyword(s):  
Plasma Membrane ◽  
Transport System ◽  
Binding Sites ◽  
Cytochalasin B ◽  
Transport Systems ◽  
Scatchard Analysis ◽  
Hexose Transport ◽  
Whole Cells ◽  
High Affinity ◽  
Binding Data

We have recently demonstrated that two hexose-transport systems are present in undifferentiated rat L6 myoblasts: D-glucose and 2-deoxy-D-glucose are preferentially transported by the high-affinity system, whereas 3-O-methyl-D-glucose is transported primarily by the low-affinity system. Mutant D23 is found to be defective only in the high-affinity hexose-transport system. The low-affinity transport system is much more sensitive to inhibition by cytochalasin B (CB). The present study examines the identity, properties and regulation of the CB-binding sites by measuring CB binding to both whole cells and plasma membrane. Scatchard analysis of the binding data revealed the presence of two CB-binding sites, namely CBH and CBL. These two sites differ not only in their affinity for CB, but their levels can also be differentially altered by various biochemical, physiological and genetic manipulations. CBL resembles the high-affinity hexose-transport system in that it is absent in mutant D23 and is present in larger quantities in glucose-starved cells. Moreover, CB binding to this site is inhibited by D-glucose and 2-deoxy-D-glucose, the preferred substrates of the high-affinity hexose-transport system. On the other hand, CBH is found to be unaltered in mutant D23, which also retains the normal low-affinity hexose-transport system. CBH also resembles the low-affinity transport system in that it is not elevated in glucose-starved cells. Furthermore, binding of CB to this site can be inhibited by 3-O-methyl-D-glucose, the preferred substrate of the low-affinity transport system. It should be noted that 2-deoxy-D-glucose does not have much effect on CBH, and vice versa. Studies with purified membrane preparations indicate that both CB-binding sites are present in similar ratios in the plasma membrane and the low-density microsomal fraction. Plasma-membrane studies also reveal that D-glucose 6-phosphate, but not 2-deoxy-D-glucose 6-phosphate, is very effective in activating CB binding. Data presented suggest that CB binding may be regulated by sugar analogues in an allosteric manner.

scholarly journals Characterization of sodium-dependent and sodium-independent nucleoside transport systems in rabbit brush-border and basolateral plasma-membrane vesicles from the renal outer cortex

1989 ◽  
Vol 264 (1) ◽  
pp. 223-231 ◽  
Author(s):  
T C Williams ◽  
A J Doherty ◽  
D A Griffith ◽  
S M Jarvis
Keyword(s):  
Brush Border ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Nucleoside Transport ◽  
Transport Systems ◽  
Facilitated Diffusion ◽  
Basolateral Membrane Vesicles ◽  
Plasma Membrane Vesicles ◽  
Outer Cortex ◽  
Overshoot Phenomenon

The transport of uridine into rabbit renal outer-cortical brush-border and basolateral membrane vesicles was compared at 22 degrees C. Uridine was taken up into an osmotically active space in the absence of metabolism for both types of membrane vesicles. Uridine influx by brush-border membrane vesicles was stimulated by Na+, and in the presence of inwardly directed gradients of Na+ a transient overshoot phenomenon was observed, indicating active transport. Kinetic analysis of the saturable Na+-dependent component of uridine flux indicated that it was consistent with Michaelis-Menten kinetics (Km 12 +/- 3 microM, Vmax. 3.9 +/- 0.9 pmol/s per mg of protein). The sodium:uridine coupling stoichiometry was found to be consistent with 1:1 and involved the net transfer of positive charge. In contrast, uridine influx by basolateral membrane vesicles was not dependent on the cation present and was inhibited by nitrobenzylthioinosine (NBMPR). NBMPR-sensitive uridine transport was saturable (Km 137 +/- 20 microM, Vmax. 5.2 +/- 0.6 pmol/s per mg of protein). Inhibition of uridine flux by NBMPR was associated with high-affinity binding of NBMPR to the basolateral membrane (Kd 0.74 +/- 0.46 nM). Binding of NBMPR to these sites was competitively blocked by adenosine and uridine. These results indicate that uridine crosses the brush-border surface of rabbit proximal renal tubule cells by Na+-dependent pathways, but permeates the basolateral surface by NBMPR-sensitive facilitated-diffusion carriers.

scholarly journals Functional Characterization of a High-Affinity Choline Transport System in Human Keratinocytes

2002 ◽  
Vol 119 (1) ◽  
pp. 118-121 ◽  
Author(s):  
Kathrin Hoffmann ◽  
Franziska Grafe ◽  
Wolfgang Wohlrab ◽  
Reinhard H. Neubert ◽  
Matthias Brandsch
Keyword(s):  
Transport System ◽  
Functional Characterization ◽  
Human Keratinocytes ◽  
Choline Transport ◽  
High Affinity

Proton gradient-dependent renal transport of glycine: evidence for vesicle studies

1990 ◽  
Vol 258 (2) ◽  
pp. F388-F396 ◽  
Author(s):  
H. Roigaard-Petersen ◽  
H. Jessen ◽  
S. Mollerup ◽  
K. E. Jorgensen ◽  
C. Jacobsen ◽  
...  
Keyword(s):  
Transport System ◽  
Membrane Vesicles ◽  
Proton Gradient ◽  
Transport Systems ◽  
Rabbit Kidney ◽  
Renal Transport ◽  
High Affinity ◽  
Luminal Membrane ◽  
Pars Recta ◽  
Pars Convoluta

The characteristics of renal transport of glycine by luminal membrane vesicles isolated from either proximal convoluted part (pars convoluta) or proximal straight part (pars recta) of rabbit proximal tubule were investigated. In vesicles from pars convoluta two transport systems have been characterized: a Na(+)-dependent system with intermediate affinity (half-saturation 3.64 mM) and a Na(+)-independent system that, in the presence of H+ gradient (extravesicular greater than intravesicular), can accelerate the transport of glycine into these vesicles. This is the first demonstration of H(+)-glycine cotransport across the luminal membrane of rabbit kidney proximal convoluted tubule. By contrast, in membrane vesicles from pars recta, transport of glycine was strictly dependent on Na+ and occurred via a dual transport system, namely a high-affinity (half-saturation 0.34 mM) and a low-affinity system (half-saturation 8.56 mM). The demonstration of competition between the H(+)-gradient dependent uptake of glycine, L-alanine, and L-proline, but insignificant inhibition with L-phenylalanine in vesicles from pars convoluta suggests that glycine, L-proline, and L-alanine probably share a common proton gradient-dependent transport system. In vesicles from pars recta, the Na(+)-dependent uptake of glycine was inhibited by low concentrations of L-alanine and L-phenylalanine, whereas addition of L-proline to the incubation medium did not significantly alter the uptake of glycine, suggesting that the Na(+)-dependent high-affinity system for glycine located in pars recta is shared with the high-affinity L-alanine and L-phenylalanine but not L-proline transport system.

scholarly journals Isolation and characterization of mutants that produce the allantoin-degrading enzymes constitutively in Saccharomyces cerevisiae.

1982 ◽  
Vol 2 (9) ◽  
pp. 1088-1095 ◽  
Author(s):  
G Chisholm ◽  
T G Cooper
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Enzyme Synthesis ◽  
Common Element ◽  
Transport Systems ◽  
New Class ◽  
Degrading Enzymes ◽  
Isolation And Characterization ◽  
Nitrogen Repression ◽  
Internal Induction

Degradation of allantoin, allantoate, or urea by Saccharomyces cerevisiae requires the participation of four enzymes and four transport systems. Production of the four enzymes and one of the active transport systems is inducible; allophanate, the last intermediate of the pathway, functions as the inducer. The involvement of allophanate in the expression of five distinct genes suggested that they might be regulated by a common element. This suggestion is now supported by the isolation of a new class of mutants (dal80). Strains possessing lesions in the DAL80 locus produce the five inducible activities at high, constitutive levels. Comparable constitutive levels of activity were also observed in doubly mutant strains (durl dal80) which are unable to synthesize allophanate. This, with the observation that arginase activity remained at its uninduced, basal level in strains mutated at the DAL80 locus, eliminates internal induction as the basis for constitutive enzyme synthesis. Mutations in dal80 are recessive to wild-type alleles. The DAL80 locus has been located and is not linked to any of the structural genes of the allantoin pathway. Synthesis of the five enzymes produced constitutively in dal80-1-containing mutants remains normally sensitive to nitrogen repression even though the dal80-1 mutation is present. From these observations we conclude that production of the allantoin-degrading enzymes is regulated by the DAL80 gene product and that induction and repression of enzyme synthesis can be cleanly separated mutationally.

scholarly journals Isolation and characterization of membrane proteins responsible for attachment of polyribosomes to rough microsomal fraction of rat liver

1977 ◽  
Vol 164 (1) ◽  
pp. 53-66 ◽  
Author(s):  
S Fujita ◽  
F Ogata ◽  
J Nakamura ◽  
S Omata ◽  
H Sugano
Keyword(s):  
Rat Liver ◽  
Protein Fraction ◽  
Microsomal Fraction ◽  
Binding Capacity ◽  
Gel Filtration ◽  
High Affinity ◽  
Isolation And Characterization ◽  
Microsomal Membranes ◽  
Equilibrium Centrifugation

A protein fraction which has a high affinity for polyribosomes was isolated from rough microsomal membranes of rat liver. The mode of polyribosome binding to this fraction (R-fraction) was studied by using CsCl equilibrium centrifugation and compared with that for stripped rough microsomal membranes. The following were found. (1) The polyribosome-binding cpacity of the R-fraction was heat-labile and sensitive to trypsin, and was suppressed by increasing KCl concentration and addition of 0.1 mM-aurintricarboxylic acid. (2) Of the four subfractions obtained by gel filtration of the R-fraction on a Sephadex G-200, only the R1-fraction, eluted at the void volume, showed a high affinity for polyribosomes. The polyribosome-binding capacity of the R1-fraction decreased with time on storage at 4 degrees C. (3) The R1-fraction contained three major proteins with mol. wts. 108,000, 99,000 and 65,000.

scholarly journals TCR-based therapy for multiple myeloma and other B-cell malignancies targeting intracellular transcription factor BOB1

Blood ◽  
2017 ◽  
Vol 129 (10) ◽  
pp. 1284-1295 ◽  
Author(s):  
Lorenz Jahn ◽  
Pleun Hombrink ◽  
Renate S. Hagedoorn ◽  
Michel G. D. Kester ◽  
Dirk M. van der Steen ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Transcription Factor ◽  
B Cell ◽  
B Cell Malignancies ◽  
High Affinity ◽  
Isolation And Characterization ◽  
Key Points

Key Points Isolation and characterization of a high-affinity TCR targeting the intracellular B cell–specific transcription factor BOB1. T cells expressing a BOB1-specific TCR lysed and eradicated primary multiple myeloma and other B-cell malignancies in vitro and in vivo.

Sign in / Sign up

Export Citation Format

Share Document