Functional expression of a myo-inositol/H+ symporter from Leishmania donovani.
The vast majority of surface molecules in such kinetoplastid protozoa as members of the genus Leishmania contain inositol and are either glycosyl inositol phospholipids or glycoproteins that are tethered to the external surface of the plasma membrane by glycosylphosphatidylinositol anchors. We have shown that the biosynthetic precursor for these abundant glycolipids, myo-inositol, is translocated across the parasite plasma membrane by a specific transporter that is structurally related to mammalian facilitative glucose transporters. This myo-inositol transporter has been expressed and characterized in Xenopus laevis oocytes. Two-electrode voltage clamp experiments demonstrate that this protein is a sodium-independent electrogenic symporter that appears to utilize a proton gradient to concentrate myo-inositol within the cell. Immunolocalization experiments with a transporter-specific polyclonal antibody reveal the presence of this protein in the parasite plasma membrane.
Drew
M E
ME
Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, Portland 97201, USA.
Langford
C K
CK
Klamo
E M
EM
Russell
D G
DG
Kavanaugh
M P
MP
Landfear
S M
SM
D000595:Amino Acid Sequence; D000818:Animals; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D002462:Cell Membrane / Q000737:chemistry; D017125:Genes, Protozoan / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007294:Inositol / Q000378:metabolism*; D017136:Ion Transport; D007700:Kinetics; D007893:Leishmania donovani / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009865:Oocytes; D011522:Protons; D015800:Protozoan Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D016415:Sequence Alignment; D027981:Symporters; D014982:Xenopus laevis
D002352:Carrier Proteins; D008565:Membrane Proteins; D011522:Protons; D015800:Protozoan Proteins; D027981:Symporters; C078009:D1 protein, Leishmania; D007294:Inositol