Reduced folate carrier transports thiamine monophosphate: an alternative route for thiamine delivery into mammalian cells
Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Although the reduced folate carrier RFC1 and the thiamine transporters THTR-1 and THTR-2 share ~40% of their identity in protein sequence, RFC1 does not transport thiamine and THTR-1 and TH...
Saved in:
Published in | American Journal of Physiology: Cell Physiology Vol. 282; no. 6; pp. C1512 - C1517 |
---|---|
Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
01.06.2002
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Departments of Medicine and Molecular Pharmacology,
Albert Einstein College of Medicine, Bronx, New York 10461
Although the reduced folate carrier
RFC1 and the thiamine transporters THTR-1 and THTR-2 share ~40% of
their identity in protein sequence, RFC1 does not transport thiamine
and THTR-1 and THTR-2 do not transport folates. In the present study,
we demonstrate that transport of thiamine monophosphate (TMP), an
important thiamine metabolite present in plasma and cerebrospinal
fluid, is mediated by RFC1 in L1210 murine leukemia cells. Transport of
TMP was augmented by a factor of five in cells (R16) that overexpress
RFC1 and was markedly inhibited by methotrexate, an RFC1 substrate, but
not by thiamine. At a near-physiological concentration (50 nM), TMP influx mediated by RFC1 in wild-type L1210 cells was ~50% of
thiamine influx mediated by thiamine transporter(s). Within 1 min, the majority of TMP transported into R16 cells was hydrolyzed to thiamine with a component metabolized to thiamine pyrophosphate, the active enzyme cofactor. These data suggest that RFC1 may be one of the alternative transport routes available for TMP in some tissues when
THTR-1 is mutated in the autosomal recessive disorder
thiamine-responsive megaloblastic anemia.
SLC19A transporters; thiamine-responsive megaloblastic anemia; thiamine pyrophosphate; thiamine homeostasis; vitamin B 1
uptake |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0363-6143 1522-1563 |
DOI: | 10.1152/ajpcell.00547.2001 |