Abstract
Polyclonal antibodies raised against the human erythrocyte nucleoside transporter were used to investigate the distribution of the nucleoside transporters in the placenta. Immunoblots of brush-border membranes isolated from the human syncytiotrophoblast revealed a cross-reactive species that co-migrated with the erythrocyte nucleoside transporter as a broad band of apparent M r 55,000. In contrast, no labelling was detected in basal membranes containing a similar number of equilibrative nucleoside transporters as assessed by nitrobenzylthioinosine (NBMPR)-binding. The absence of cross-reactive epitopes in basal membranes and their presence in brush-border membranes was confirmed by confocal immunofluorescence microscopy. These results suggest that at least two isoforms of the NBMPR-sensitive nucleoside transporter are present in the human placenta. The lumenal surfaces of fetal capillaries, small placental vessels and umbilical vein were also strongly labelled by the antibody, a finding that suggests that the high fetal-placental adenosine uptake previously reported is due to endothelial transporters.
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Abbreviations
- NT :
-
The human erythrocyte nucleoside transporter
- Anti-NT :
-
Polyclonal antibody against the nucleoside transporter
- NBMPR :
-
Nitrobenzylthioinosine {6-[(4-nitrobenzyl)thio]-9-β-D-ribofuranosylpurine}.
- GLUTl :
-
The human erythrocyte glucose transporter
- PBS :
-
Phosphate-buffered saline
- TBS :
-
TRIS-buffered saline
- TTBS :
-
TRIS-buffered saline containing 0.2% Tween-20
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Barros, L.F., Yudilevich, D.L., Jarvis, S.M. et al. Immunolocalisation of nucleoside transporters in human placental trophoblast and endothelial cells: evidence for multiple transporter isoforms. Pflugers Arch. 429, 394–399 (1995). https://doi.org/10.1007/BF00374155
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DOI: https://doi.org/10.1007/BF00374155