Acidic Amino Acids in the First Intracellular Loop Contribute to Voltage- and Calcium- Dependent Gating of Anoctamin1/TMEM16A

C1 is a transcriptional activator of genes encoding biosynthetic enzymes of the maize anthocyanin pigment pathway. C1 has an amino terminus homologous to Myb DNA-binding domains and an acidic carboxyl terminus that is a transcriptional activation domain in maize and yeast cells. To identify amino acids critical for transcriptional activation, an extensive random mutagenesis of the C1 carboxyl terminus was done. The C1 activation domain is remarkably tolerant of amino acid substitutions, as changes at 34 residues had little or no effect on transcriptional activity. These changes include introduction of helix-incompatible amino acids throughout the C1 activation domain and alteration of most single acidic amino acids, suggesting that a previously postulated amphipathic alpha-helix is not required for activation. Substitutions at two positions revealed amino acids important for transcriptional activation. Replacement of leucine 253 with a proline or glutamine resulted in approximately 10% of wild-type transcriptional activation. Leucine 253 is in a region of C1 in which several hydrophobic residues align with residues important for transcriptional activation by the herpes simplex virus VP16 protein. However, changes at all other hydrophobic residues in C1 indicate that none are critical for C1 transcriptional activation. The other important amino acid in C1 is aspartate 262, as a change to valine resulted in only 24% of wild-type transcriptional activation. Comparison of our C1 results with those from VP16 reveal substantial differences in which amino acids are required for transcriptional activation in vivo by these two acidic activation domains.

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Amino acid transport by juxtamedullary nephrons: distal reabsorption and recycling

AJP Renal Physiology ◽

10.1152/ajprenal.1988.255.3.f397 ◽

1988 ◽

Vol 255 (3) ◽

pp. F397-F407 ◽

Cited By ~ 2

Author(s):

W. H. Dantzler ◽

S. Silbernagl

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Amino Acid Transport ◽

Acid Transport ◽

Acidic Amino Acids ◽

Vasa Recta ◽

Collecting Ducts ◽

Distal Site

Amino acid transport by juxtamedullary (JM) nephrons and its relationship to transport by superficial cortical (SC) nephrons and to function of vasa recta and collecting ducts were examined in vivo and in situ by free-flow micropuncture of Henle's loops, collecting ducts, and vasa recta and by continuous microinfusion of Henle's loops in exposed rat papillae. Fractional deliveries (FDs) of six neutral amino acids, two acidic amino acids, and taurine to tips of Henle's loops of JM nephrons could be substantially below those to early distal loops of SC nephrons, indicating that reabsorption before loop tips could be greater in JM than in SC nephrons. FDs to collecting ducts lower than to JM loop tips suggested reabsorption distal to loop tips. This was confirmed by continuous microinfusion of ascending limbs of Henle's loops. Distal site of reabsorption is unknown, but amino acids may move passively out of the thin ascending limb and be recycled into vasa recta and descending limb. Recycling of amino acids was supported by high FDs to tips of Henle's loops (sometimes greater than 1.0), higher concentrations in ascending than in descending vasa recta at same papilla level, and high mean concentrations in vasa recta.

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Uptake and asymmetric efflux of amino acids at maternal and fetal sides of placenta

AJP Cell Physiology ◽

10.1152/ajpcell.1981.241.3.c106 ◽

1981 ◽

Vol 241 (3) ◽

pp. C106-C112 ◽

Cited By ~ 46

Author(s):

B. M. Eaton ◽

D. L. Yudilevich

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Guinea Pig ◽

Cellular Uptake ◽

Transport Systems ◽

Acid Transport ◽

Dilution Technique ◽

Acidic Amino Acids ◽

Tracer Dilution ◽

Paired Tracer Dilution

Unidirectional uptake of eighteen amino acids into the syncytiotrophoblast was measured from both the maternal and fetal circulations of isolated dually perfused guinea pig placentas using a single-circulation, paired-tracer dilution technique. A bolus containing a tritiated amino acid and L-[14C]glucose (extracellular marker) was injected intra-arterially into one circulation, and both venous outflows were sequentially sampled. The maximal cellular uptake (Umax) on the injection side was determined from (1-[3H]/[14C]) values and used to calculate the unidirectional influx. Umax values for neutral and basic amino acids ranged between 15 and 58% and were similar on both sides of the trophoblast. Uptake of the acidic amino acids and taurine was minimal. Amino acid influx from either circulation was followed by rapid tracer backflux and transplacental transfer. Tracer efflux was asymmetric and preferentially directed towards the fetal side. It is suggested that amino acid transport systems are present on both surfaces of the placenta and that net transfer from mother to fetus is the result of asymmetric efflux from the trophoblast.

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Structural factors influencing the reaction rates of 4-aryloxy-7-nitrobenzofurazans with amino acids

Open Chemistry ◽

10.2478/bf02482730 ◽

2004 ◽

Vol 2 (4) ◽

pp. 672-685 ◽

Cited By ~ 2

Author(s):

Marioara Bem ◽

Marilena Vasilescu ◽

Miron Caproiu ◽

Constantin Draghici ◽

Adrian Beteringhe ◽

...

Keyword(s):

Amino Acids ◽

Room Temperature ◽

Reaction Rates ◽

Structural Factors ◽

Basic Amino Acids ◽

Interesting Observation ◽

Neutral Amino Acids ◽

Acidic Amino Acids ◽

Factors Influencing ◽

Snar Reaction

AbstractAn interesting observation was made when studying the SNAr reaction between several 4-aryloxy-7-nitrobenzofurazans (2) and several amino acids leading to the apparition of detectable fluorescence from the substitution products3. Acidic amino acids reacted very slowly=while basic amino acids react fastest with2 having an unsubstituted phenyl or a 4-formyl-phenyl Ar group. Amongst neutral amino acids, proline reacts fastest at room temperature after 100 min. With2 having a methoxy-subtituted Ar group.

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Electrical Evidence for Different Mechanisms of Uptake for Basic, Neutral, and Acidic Amino Acids in Oat Coleoptiles

PLANT PHYSIOLOGY ◽

10.1104/pp.65.6.1085 ◽

1980 ◽

Vol 65 (6) ◽

pp. 1085-1089 ◽

Cited By ~ 50

Author(s):

Thomas B. Kinraide ◽

Bud Etherton

Keyword(s):

Amino Acids ◽

Acidic Amino Acids

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Acidic amino acids evoke a smaller [Ca2+]i rise in GABAergic than non-GABAergic hippocampal neurons

Neuroscience Letters ◽

10.1016/0304-3940(92)90112-k ◽

1992 ◽

Vol 140 (2) ◽

pp. 243-246 ◽

Cited By ~ 8

Author(s):

Menahem Segal ◽

Varda Greenberger

Keyword(s):

Amino Acids ◽

Hippocampal Neurons ◽

Acidic Amino Acids

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Purification of an exo-1,3-β-glucanase from Candida utilis

Canadian Journal of Biochemistry ◽

10.1139/o76-134 ◽

1976 ◽

Vol 54 (11) ◽

pp. 927-934 ◽

Cited By ~ 19

Author(s):

T. G. Villa ◽

V. Notario ◽

T. Benítez ◽

J. R. Villanueva

Keyword(s):

Amino Acids ◽

Heavy Metal ◽

Cell Wall ◽

Heavy Metal Ions ◽

Candida Utilis ◽

Negative Charge ◽

Hydrolysis Product ◽

Culture Fluid ◽

Biochemical Properties ◽

Acidic Amino Acids

An exo-1,3-β-glucanase (EC 3.2.1.—) has been purified from the culture fluid of the yeast Candida utilis, and its biochemical properties have been studied. The amino acid analysis revealed a high content of acidic amino acids. The purified enzyme had 20% carbohydrate and a net negative charge showing higher affinity for laminarin than for p-nitrophenyl-β-D-glucopyranoside and yeast cell-wall 1,3-β-glucans. In addition, the enzyme hydrolyzed the substrates starting from the nonreducing ends, releasing glucose as the exclusive hydrolysis product. The enzyme activity was strongly inhibited by lactones and also by some heavy-metal ions.

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