L-serine uptake by human placental microvillous membrane vesicles
Lewis, R.M., Glazier, J., Greenwood, S.L., Bennett, E.J., Godfrey, K.M., Jackson, A.A., Sibley, C.P., Cameron, I.T. and Hanson, M.A. (2007) L-serine uptake by human placental microvillous membrane vesicles. Placenta, 28, (5-6), 445-452. (doi:10.1016/j.placenta.2006.06.014).
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Description/Abstract
The human fetus requires more glycine than any other amino acid but placental glycine transfer to the fetus is insufficient to meet fetal demand. L-Serine could represent a major metabolic source of glycine for the human fetus but little is known about the kinetics and physiology of L-serine uptake by the human placenta. We have characterised the amino acid transport systems involved in the uptake of L-serine by the microvillous membrane of the human placental syncytiotrophoblast and compared the uptake rates to those of glycine. L-Serine uptake into microvillous membrane (MVM) vesicles was primarily mediated by system A (MeAIB inhibitable) and system L (BCH inhibitable). Further characterisation using specific substrates of LAT1 and LAT2 found the pattern of L-serine uptake was consistent with that expected for uptake mediated by LAT2. Uptakes were performed with tracer levels of (14)C-L-serine, physiological levels of L-serine, or with physiological levels of amino acids. As amino acid concentrations rose, the proportion of uptake by System L decreased while uptake by uncharacterised Na(+)-independent systems increased. Uptake of Lserine into MVM vesicles had a V(max) of 2.1+/-0.4 nmol/mg protein/min, which was significantly higher than for glycine (V(max) 1.0+/-0.2 nmol/mg protein/min). This indicates that MVM vesicles have a higher uptake capacity for L-serine than glycine, despite a greater demand for glycine over serine for fetal protein synthesis. Further studies are now required to define the fate of L-serine taken up by the placenta and its importance for the fetus.
| Item Type: | Article |
|---|---|
| ISSNs: | 0143-4004 (print) |
| Related URLs: | |
| Keywords: | acid, antigens, health, sodium-calcium exchanger, pregnancy, amino acid transport system a, amino acid transport system y+, glycine, kinetics, origins, cd98 light chains, genetics, biological transport, fetus, disease, female, amino acids, microvilli, serine, placenta, human, amino acid transport system y+l, research, neoplasm proteins, fetal, proteins, protein, physiology, metabolism, amino acid transport systems, humans, membrane |
| Subjects: | R Medicine > RG Gynecology and obstetrics Q Science > QH Natural history > QH301 Biology |
| Divisions: | University Structure - Pre August 2011 > School of Medicine |
| Item ID: | 61327 |
| Date Deposited: | 10 Sep 2008 |
| Last Modified: | 02 Mar 2012 12:12 |
| Contributors: | Lewis, R.M. (Author) Glazier, J. (Author) Greenwood, S.L. (Author) Bennett, E.J. (Author) Godfrey, K.M. (Author) Jackson, A.A. (Author) Sibley, C.P. (Author) Cameron, I.T. (Author) Hanson, M.A. (Author) |
| Date: | May 2007 |
| Status: | Published |
| URI: | http://eprints.soton.ac.uk/id/eprint/61327 |
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