Functional expression cloning and characterization of SFT, a stimulator of Fe transport.
A stimulator of Fe transport (SFT) was identified by functional expression cloning in Xenopus oocytes. SFT-mediated transport has properties defined for transferrin-independent Fe uptake, but its cytolocalization in recycling endosomes and the observed stimulation of transferrin-bound Fe assimilation indicate a key role in intracellular Fe membrane transport as well. SFT has six predicted transmembranous domains and a functionally important RExxE motif that resembles domains involved in yeast Fe transport and Fe-binding by ferritin L-chains. The observation that SFT oligomerizes, along with other structural and mechanistic features, suggests it may be a member of either the ATP-binding cassette or cation diffusion facilitator families. The 3' untranslated region of SFT contains a translation inhibitory element and inhibition of SFT expression in Xenopus oocytes was found to be relieved by coinjection of transcripts from other defined cDNAs that are also described in this report. SFT is the first component of the mammalian Fe membrane transport machinery to be identified.
Gutierrez
J A
JA
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Yu
J
J
Rivera
S
S
Wessling-Resnick
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D003001:Cloning, Molecular; D016384:Consensus Sequence; D011992:Endosomes / Q000378:metabolism; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D007501:Iron / Q000378:metabolism*; D033862:Iron-Binding Proteins; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014168:Transferrin / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes; D014982:Xenopus laevis
D002352:Carrier Proteins; D033862:Iron-Binding Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D014168:Transferrin; D007501:Iron; C097308:UBE2D1 protein, human; D044763:Ubiquitin-Conjugating Enzymes