Inhibition of ATB0,+ -mediated glycine uptake in HRPE cells by the derivatives of aspartate and glutamate
Mouse ATB0,+ cDNA was expressed functionally in HRPE cells by the vaccinia virus expression technique. The transport activity of ATB0,+ was monitored by the uptake of 10 μM glycine in the presence of NaCl. Uptake was measured in the absence (control, 100%) and presence of 1 mM aspartate, glutamate, or their derivatives.
Amino Acid Derivative | ATB0,+ -Specific Glycine Transport |
|---|---|
| % | |
| None | 100 ± 5 |
| l-Aspartate | 86 ± 3 |
| l-Asparagine | 22 ± 0 |
| l-Aspartate β-methylester | 8 ± 1 |
| l-Aspartate β-benzylester | 2 ± 1 |
| l-Aspartate β-hydroxamate | 39 ± 1 |
| l-Aspartate β-(7-amido-4-methylcoumarin) | 92 ± 5* |
| N-β-l-Aspartyl-l-phenylalanyl methylester | 62 ± 3 |
| l-Glutamate | 82 ± 2 |
| l-Glutamine | 21 ± 1 |
| l-Glutamate γ-benzylester | 13 ± 1 |
| dl-Glutamate γ-anilide | 49 ± 1 |
| l-Glutamate γ-(α-naphthylamide) | 97 ± 2 |
| l-Glutamate γ-(β-naphthylamide) | 79 ± 4* |
↵* Due to limited solubility, l-aspartate β-(7-amido-4-methylcoumarin) and l-glutamate γ-(β-nephthylamide) were used at 0.25 mM instead of 1 mM. Results are given as percentage of control uptake.