Amino acid uptake by Saccharomyces cerevisiae plasma membrane vesicles

1980 ◽  
Vol 595 (1) ◽  
pp. 109-120 ◽  
Author(s):  
Glenn J. Merkel ◽  
Fred Naider ◽  
Jeffrey M. Becker
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Amino Acid ◽  
Membrane Vesicles ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Plasma Membrane Vesicles

scholarly journals Amino acid uptake by liver of genetically obese Zucker rats

1991 ◽  
Vol 280 (2) ◽  
pp. 367-372 ◽  
Author(s):  
B Ruiz ◽  
A Felipe ◽  
J Casado ◽  
M Pastor-Anglada
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Membrane Vesicles ◽  
Amino Acid Uptake ◽  
Zucker Rats ◽  
Acid Uptake ◽  
Plasma Membrane Vesicles ◽  
Net Uptake ◽  
Obese Zucker Rats

Alanine and glutamine uptake by the liver of 50-52-day-old genetically obese Zucker rats and their lean littermates has been studied. The net uptake in vivo of L-alanine is 2-fold higher in the obese animals. No significant change in L-glutamine net balance was found. We also studied the Na(+)-dependent uptake of L-alanine and L-glutamine into plasma-membrane vesicles isolated from either obese- or lean-rat livers. Vmax. values of both L-alanine and L-glutamine transport were 2-fold higher in those preparations from obese rats. No change in Km was observed. As suggested by inhibition studies, this seemed to be mediated by an enhancement of the activities of systems A, ASC and N. We conclude that the liver of the obese Zucker rat is extremely efficient in taking up neutral amino acids from the afferent blood, which results in an enhanced net uptake of L-alanine in vivo. The changes in transport activities at the plasma-membrane level might contribute to increase amino acid disposal by liver, probably for lipogenic purposes, as recently reported by Terrettaz & Jeanrenaud [Biochem. J. (1990) 270, 803-807].

Kinetic and energetic aspects of the inhibition of taurocholate uptake by Na+-dependent amino acids: studies in rat liver plasma membrane vesicles

1985 ◽  
Vol 249 (1) ◽  
pp. G120-G124
Author(s):  
B. L. Blitzer ◽  
R. L. Bueler
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Bile Acid ◽  
Amino Acid ◽  
Initial Velocity ◽  
Membrane Vesicles ◽  
Acid Uptake ◽  
Plasma Membrane Vesicles ◽  
Liver Plasma Membrane ◽  
Bile Acid Uptake

The kinetic and energetic aspects of the inhibition of taurocholate uptake by the Na+-dependent amino acid L-alanine were studied in rat basolateral liver plasma membrane vesicles. In the presence of an inwardly directed Na+ gradient, alanine (5 mM) reduced the initial velocity of taurocholate uptake to 60% of control and virtually abolished the overshoot. In the presence of a K+ gradient, the slow rate of Na+-independent taurocholate uptake was similar in the presence or absence of the amino acid. Inhibition of Na+-dependent taurocholate uptake increased nonlinearly with alanine concentration (half-maximal inhibition at approximately 1 mM) and plateaued at 5–10 mM. Kinetic studies showed that alanine significantly reduced the Vmax for taurocholate uptake from 6.32 +/- 0.22 to 3.68 +/- 0.21 nmol X mg prot-1 X min-1 but did not significantly affect taurocholate Km (38.4 +/- 3.6 vs. 29.0 +/- 4.9 microM). In contrast, the Na+-independent amino acid 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid did not affect either the initial velocity or peak uptake of taurocholate. The effects of alanine on the driving forces for bile acid uptake were directly assessed by measuring vesicle uptake of 22Na. At early time points, 22Na uptake was faster in the presence of alanine than under control conditions. These findings provide further evidence that Na+-dependent amino acids noncompetitively inhibit Na+-dependent bile acid uptake in association with accelerated dissipation of the transmembrane Na+ gradient and extend previous observations of this phenomenon made in isolated rat hepatocytes [Am. J. Physiol. 245 (Gastrointest. Liver Physiol. 8): G399-G403, 1983].

Myocardial amino acid transport by canine sarcolemma vesicles

1987 ◽  
Vol 252 (6) ◽  
pp. H1070-H1076
Author(s):  
L. H. Young ◽  
B. L. Zaret ◽  
E. J. Barrett
Keyword(s):  
Amino Acid ◽  
Sarcoplasmic Reticulum ◽  
Membrane Vesicles ◽  
Amino Acid Uptake ◽  
Ventricular Myocardium ◽  
Transport Systems ◽  
Acid Uptake ◽  
Leucine Uptake ◽  
Alanine Transport ◽  
Canine Ventricular Myocardium

The transport of L-alanine and L-leucine into membrane vesicles isolated from mature canine ventricular myocardium was studied. Transport was assessed in purified sarcolemma and in vesicles differentially enriched either for sarcolemma or sarcoplasmic reticulum to further localize these transport systems. An imposed inward gradient of a NaNO3 stimulated uptake of L-alanine but not L-leucine by these vesicles. Amino acid uptake by these vesicles occurred into an osmotically active space. The stimulatory effect of Na+ on alanine transport was most striking in the purified sarcolemma vesicles, where Na+-stimulated alanine flux was 45 +/- 14 pmol X mg-1 X min-1. Furthermore, Na+-dependent alanine transport activity appeared to copurify with Na+-K+-ATPase activity, which served as a marker for sarcolemma membrane when these activities were compared in the three different membrane preparations. Leucine transport by sarcolemma was not altered by an imposed Na+ gradient. However, leucine uptake was a saturable function of extravesicular leucine and was inhibited by valine. In contrast, in sarcoplasmic reticulum membrane vesicles leucine uptake increased proportionately with increasing media leucine and was unaffected by valine. Our results demonstrate the feasibility of directly studying the transport of naturally occurring amino acids in membrane vesicles from mammalian heart, and the presence of Na+-dependent alanine transport system and a Na+-independent leucine transporter in the sarcolemma but not in sarcoplasmic reticulum of canine ventricular myocardium.

Electroimmunochemical analysis of plasma membrane vesicles from Saccharomyces cerevisiae

1982 ◽  
Vol 60 (6) ◽  
pp. 659-667
Author(s):  
James H. Gerlach ◽  
Ole J. Bjerrum ◽  
Gerald H. Rank
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Concanavalin A ◽  
Periodic Acid ◽  
Membrane Vesicles ◽  
Free Form ◽  
Plasma Membrane Vesicles ◽  
Crossed Immunoelectrophoresis ◽  
Lentil Lectin ◽  
Triton X

Plasma membrane vesicles of Saccharomyces cerevisiae were extracted with 1% (w/v) Triton X-100 and the solubilized proteins examined by crossed immunoelectrophoresis using rabbit antibodies against the vesicles. Solubilization was shown to be nonselective and 23 immunoprecipitates were observed reproducibly.Four glycoproteins were identified by interaction with concanavalin A and lentil lectin, either immobilized on agarose beads in an intermediate gel or incorporated in the free form in the first dimension gel. One glycoprotein was stainable by the periodic acid – Schiff procedure. None of the glycoproteins had their origin in the cell wall.Five amphiphilic proteins were identified on the basis of charge-shift and hydrophobic interaction crossed immunoelectrophoresis as well as [14C]Triton X-100 and Sudan black B binding. Three of the amphiphilic proteins were also glycoproteins.Based on the carbohydrate content and amphiphilic properties of the proteins, purification schemes using concanavalin A-Sepharose and phenyl-Sepharose were proposed. Trial separations using 1-mL columns were monitored by fused rocket and crossed immunoelectrophoresis.

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