Development and polarization of cationic amino acid transporters and regulators in the human placenta

Paul T Y Ayuk, Colin P. Sibley, Paul Donnai, Stephen D'Souza, Jocelyn D. Glazier

    Research output: Contribution to journalArticlepeer-review


    We have investigated L-arginine transport systems in the human placental syncytiotrophoblast across gestation using purified microvillous (MVM) and basal (BM) plasma membrane vesicles. In MVM from first-trimester and term placentas, L-arginine transport was by systems y+ and y+L. In BM (term placentas), however, there was evidence for system y+L only. The Michaelis constant of system y+L was significantly lower (P <0.05) in first-trimester compared with term MVM and lower in term MVM compared with BM (P <0.05). There was no functional evidence for system b0+ in term MVM or BM. Cationic amino acid transporter (CAT) 1, CAT 4, and 4F2hc were detected using RT-PCR in placentas throughout gestation, rBAT was not detected in term placentas. An ~85-kDa and an ~135-kDa protein was detected by Western blotting in MVM under reducing and nonreducing conditions, respectively, consistent with the 4F2hc monomer and the 4F2hc-light chain dimer, and their expression was significantly higher (P <0.05) in term compared with first-trimester MVM. These proteins were not detected in BM despite functional evidence for system y+L. These data suggest different roles for 4F2hc in the development and polarization of cationic amino acid transporters in the syncytiotrophoblast.
    Original languageEnglish
    Pages (from-to)C1162-C1171
    JournalAmerican Journal of Physiology: Cell Physiology
    Issue number6
    Publication statusPublished - 2000


    • 4F2hc
    • CAT 1
    • CAT 4
    • Gestational change
    • L-arginine
    • RBAT


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