Placental uric acid transport system and its impact on fetal development

Influx of phenylalanine across the brush border of rabbit intestine is markedly reduced by treatment with 5 mM p-chloromercuriphenyl sulfonate (PCMBS). The effect is rapidly and completely reversed by dithiothreitol. Phenylalanine influx into PCMBS-treated tissue can be competitively inhibited by other neutral amino acids and follows saturation kinetics. PCMBS causes an increase in the apparent Michaelis constant from the value observed in control tissue but does not alter the maximal influx significantly. Treatment of the tissue with PCMBS leads to a significant reduction in the Na-sensitivity of the transport, and a number of results indicate that the major effect of the reagent is to cause a marked reduction in the affinity of the transport system for Na. The transport system can be partially protected against reaction with PCMBS by phenylalanine and tryptophan but not by methionine or norleucine. The results suggest that PCMBS reacts with a sulfhydryl group in the region of the transport site and may alter conformational changes associated with the binding of substrates.

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Reconstitution of Pseudomonas aeruginosa High-Affinity Branched-Chain Amino Acid Transport System

Branched-Chain Amino Acids, Part B - Methods in Enzymology ◽

10.1016/s0076-6879(00)24225-0 ◽

2000 ◽

pp. 122-129

Author(s):

Toshimitsu Hoshino ◽

Yoshihiko Uratani

Keyword(s):

Pseudomonas Aeruginosa ◽

Amino Acid ◽

Transport System ◽

Amino Acid Transport ◽

Acid Transport ◽

Amino Acid Transport System ◽

High Affinity ◽

Branched Chain Amino Acid ◽

Branched Chain

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Common gene variants interactions related to uric acid transport are associated with knee osteoarthritis susceptibility

Connective Tissue Research ◽

10.1080/03008207.2018.1483359 ◽

2018 ◽

Vol 60 (3) ◽

pp. 219-229 ◽

Cited By ~ 2

Author(s):

Javier Fernández-Torres ◽

Gabriela Angélica Martínez-Nava ◽

Francesca Oliviero ◽

Alberto Gabriel López-Reyes ◽

Karina Martínez-Flores ◽

...

Keyword(s):

Uric Acid ◽

Knee Osteoarthritis ◽

Gene Variants ◽

Acid Transport ◽

Common Gene

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Expression and regulation of 4F2hc and hLAT1 in human trophoblasts

AJP Cell Physiology ◽

10.1152/ajpcell.2002.282.1.c196 ◽

2002 ◽

Vol 282 (1) ◽

pp. C196-C204 ◽

Cited By ~ 46

Author(s):

Yoko Okamoto ◽

Masahiro Sakata ◽

Kazuhiro Ogura ◽

Toshiya Yamamoto ◽

Masaaki Yamaguchi ◽

...

Keyword(s):

Amino Acid ◽

Cell Line ◽

Transport System ◽

Human Placenta ◽

Amino Acid Transport ◽

Calcium Ionophore ◽

Acid Transport ◽

Amino Acid Transport System ◽

System L ◽

Choriocarcinoma Cell Line

The neutral amino acid transport system L is a sodium-independent transport system in human placenta and choriocarcinoma cells. Recently, it was found that the heterodimer composed of hLAT1 (a light-chain protein) and 4F2 heavy chain (4F2hc), a type II transmembrane glycoprotein, is responsible for system L amino acid transport. We found that the mRNAs of 4F2hc and hLAT1 were expressed in the human placenta and a human choriocarcinoma cell line. The levels of the 4F2hc and hLAT1 proteins in the human placenta increased at full term compared with those at midtrimester. Immunohistochemical data showed that these proteins were localized mainly in the placental apical membrane. Data from leucine uptake experiments, Northern blot analysis, and immunoblot analysis showed that this transport system was partially regulated by protein kinase C and calcium ionophore in the human choriocarcinoma cell line. Our results suggest that the heterodimer of 4F2hc and hLAT1 may play an important role in placental amino acid transport system L.

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