Vba5p, a Novel Plasma Membrane Protein Involved in Amino Acid Uptake and Drug Sensitivity inSaccharomyces cerevisiae

2012 ◽  
Vol 76 (10) ◽  
pp. 1993-1995 ◽  
Author(s):  
Masamitsu SHIMAZU ◽  
Teruhiro ITAYA ◽  
Pongsanat PONGCHAROEN ◽  
Takayuki SEKITO ◽  
Miyuki KAWANO-KAWADA ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Membrane Protein ◽  
Drug Sensitivity ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Plasma Membrane Protein

scholarly journals Localization of TGN38 to the trans-Golgi network: involvement of a cytoplasmic tyrosine-containing sequence.

1993 ◽  
Vol 120 (5) ◽  
pp. 1123-1135 ◽  
Author(s):  
J S Humphrey ◽  
P J Peters ◽  
L C Yuan ◽  
J S Bonifacino
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Membrane Protein ◽  
Protein Localization ◽  
Chimeric Proteins ◽  
Plasma Membrane Protein ◽  
Intracellular Vesicles ◽  
Golgi Network ◽  
Amino Acid Segment ◽  
Cytoplasmic Determinants

Protein localization to the TGN was investigated by examining the subcellular distribution of chimeric proteins in which the cytoplasmic and/or transmembrane domains of the TGN protein, TGN38, were substituted for the analogous domains of the plasma membrane protein, Tac. Using immunofluorescence and immunoelectron microscopy, the COOH-terminal cytoplasmic domain of TGN38 was found to be sufficient for localization of the chimeric proteins to the TGN. Deletion analysis identified an 11-amino acid segment containing the critical sequence, YQRL, as being sufficient for TGN localization. TGN localization was abrogated by mutation of the tyrosine or leucine residues in this sequence to alanine, or of the arginine residue to aspartate. In addition to specifying TGN localization, the 11-amino acid segment was active as an internalization signal, although the property of internalization alone was insufficient to confer TGN localization. Overexpression of chimeric proteins containing TGN localization determinants resulted in their detection at the plasma membrane and in intracellular vesicles, and abolished detection of endogenous TGN38. These results suggest that discrete cytoplasmic determinants can mediate protein localization to the TGN, and reveal a novel role for tyrosine-based motifs in this process.

scholarly journals Components of a Ubiquitin Ligase Complex Specify Polyubiquitination and Intracellular Trafficking of the General Amino Acid Permease

2001 ◽  
Vol 153 (4) ◽  
pp. 649-662 ◽  
Author(s):  
Stephen B. Helliwell ◽  
Sascha Losko ◽  
Chris A. Kaiser
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Nitrogen Source ◽  
Ubiquitin Ligase ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Amino Acid Permease ◽  
Intracellular Targeting ◽  
Ubiquitin Ligase Complex ◽  
General Amino Acid Permease

Gap1p, the general amino acid permease of Saccharomyces cerevisiae, is regulated by intracellular sorting decisions that occur in either Golgi or endosomal compartments. Depending on nitrogen source, Gap1p is transported to the plasma membrane, where it functions for amino acid uptake, or to the vacuole, where it is degraded. We found that overexpression of Bul1p or Bul2p, two nonessential components of the Rsp5p E3–ubiquitin ligase complex, causes Gap1p to be sorted to the vacuole regardless of nitrogen source. The double mutant bul1Δ bul2Δ has the inverse phenotype, causing Gap1p to be delivered to the plasma membrane more efficiently than in wild-type cells. In addition, bul1Δ bul2Δ can reverse the effect of lst4Δ, a mutation that normally prevents Gap1p from reaching the plasma membrane. Evaluation of Gap1p ubiquitination revealed a prominent polyubiquitinated species that was greatly diminished in a bul1Δ bul2Δ mutant. Both a rsp5-1 mutant and a COOH-terminal truncation of Gap1p behave as bul1Δ bul2Δ, causing constitutive delivery of Gap1p to the plasma membrane and decreasing Gap1p polyubiquitination. These results indicate that Bul1p and Bul2p, together with Rsp5p, generate a polyubiquitin signal on Gap1p that specifies its intracellular targeting to the vacuole.

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].

Influence of insulin on amino acid uptake by lung slices

1977 ◽  
Vol 42 (2) ◽  
pp. 216-220 ◽  
Author(s):  
C. A. Gregorio ◽  
D. Massaro
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Amino Acid ◽  
Kinetic Analysis ◽  
Concentration Gradient ◽  
Diffusion Constant ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Rat Lung ◽  
Energy Dependent

We examined the transport of amino acids by rat lung slices using mainly 14C-labeled alpha-aminoisobutyric acid ([14C]AIB) as a nonmetabolized amino acid. We found that [14C]AIB is accumulated by the lung in an energy-dependent fashion against a concentration gradient. The uptake is saturable, stereospecific, and follows Michaelis-Menten kinetics suggesting enzyme or carrier mediation across the plasma membrane. Insulin increases the uptake of [14C]AIB and insulin plus glucose increases its uptake even more. The diffusion constant (KD) in the presence of glucose, insulin, or glucose plus insulin is the same, 0.29 h-1; the Vmax is also the same, 83.0 mmol-1–1-h-1, under these three conditions. The apparent Km is 14.0 mM with glucose, 9.0 mM with insulin, and 4.0 mM in the presence of glucose and insulin. We conclude that the uptake of [14C]AIB is increased by insulin, and insulin plus glucose, and, based on this kinetic analysis, this is due to an increased affinity of the transport sites for AIB (decreased Km, unchanged Vmax, and KD).

scholarly journals ATA2-mediated amino acid uptake following partial hepatectomy is regulated by redistribution to the plasma membrane

2002 ◽  
Vol 400 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Thomas L. Freeman ◽  
Geoffrey M. Thiele ◽  
Dean J. Tuma ◽  
Tina K. Machu ◽  
Mark E. Mailliard
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Partial Hepatectomy ◽  
Amino Acid Uptake ◽  
Acid Uptake

Effects of ethanol on amino acid transport in basolateral liver plasma membrane vesicles

1989 ◽  
Vol 256 (3) ◽  
pp. G458-G465
Author(s):  
R. H. Moseley ◽  
S. M. Murphy
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Maximum Velocity ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Acid Transport ◽  
Liver Plasma Membrane ◽  
Alanine Transport ◽  
Cysteine Uptake

Ethanol has been reported to inhibit hepatocellular processes such as gluconeogenesis and protein synthesis that depend, in part, on amino acid uptake. Since previous studies in cultured hepatocytes indicate that ethanol may have a direct and selective inhibitory effect on amino acid transport, the effects of ethanol on amino acid uptake into basolateral (sinusoidal) rat liver plasma membrane (blLPM) vesicles were examined. Uptake of [3H]alanine, [3H]leucine, and [35S]cysteine was measured by a rapid Millipore filtration technique in the presence of inwardly directed Na+ and K+ gradients and under tetramethylammonium (TMA+)- and Na+-equilibrated conditions. Ethanol preincubation produced a concentration-dependent inhibition of Na+-dependent alanine and cysteine uptake; no effect was observed on either Na+-independent alanine and cysteine uptake or Na+-independent leucine transport. Ethanol had no effect on L-alanine transport under Na+-equilibrated conditions; however, initial rates of 22Na flux were enhanced in the presence of ethanol. On the basis of differences in 2-(methylamino)isobutyrate and L-cysteine sensitivity, ethanol inhibition of Na+-dependent alanine transport in blLPM vesicles largely but not exclusively corresponded to the hormone-responsive system A for amino acid transport described in isolated hepatocytes. Kinetic analysis showed that ethanol treatment resulted in an alteration in the apparent maximum velocity of reaction (Vmax) of Na+-dependent alanine transport without affecting the apparent Km for alanine. The inhibitory effects of ethanol on the time course of Na+-dependent alanine uptake were reversible.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document