Cloning and functional expression of a Na(+)-dependent phosphate co-transporter from human kidney: cDNA cloning and functional expression.
A cDNA clone encoding a protein 69% identical in amino acid sequence with that of the Na/P(i) co-transporter NaP(i)-1 was isolated from a human kidney cDNA library. The DNA sequence was identical with that of NPT-1 cDNA published by Chong, Kristjansson, Zoghbi and Hughe (1993) (Genomics, 18, 355-359). In the present study, we have characterized the function of the encoded protein and the tissue distribution of its mRNA. Injection of RNA transcribed from NPT-1 into Xenopus oocytes resulted in expression of Na/P(i) co-transport activity showing a high affinity for P(i) transport (Km 0.29 mM). Kinetic characterization ([P(i)], [Na+]) demonstrated that the expressed transport activity has properties similar to those displayed by oocytes injected with human kidney poly(A)+ RNA. Northern blotting demonstrated that NPT-1 mRNA is expressed in renal cortex, liver and brain but not in other tissues. Hybrid depletion with antisense oligonucleotides to NaP(i)-3 and NPT-1 completely inhibited poly(A)+ RNA-induced Na(+)-dependent P(i) uptake in oocytes. These findings indicate that two high-affinity Na/P(i) cotransporters (NaP(i)-3 and NPT-1) are present in human kidney cortex.
Miyamoto
K
K
Department of Clinical Nutrition, School of Medicine, University of Tokushima, Japan.
Tatsumi
S
S
Sonoda
T
T
Yamamoto
H
H
Minami
H
H
Taketani
Y
Y
Takeda
E
E
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D005260:Female; D015698:Genomic Library; D006801:Humans; D007672:Kidney Cortex / Q000737:chemistry* / Q000502:physiology*; D007700:Kinetics; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010710:Phosphates / Q000493:pharmacokinetics; D016133:Polymerase Chain Reaction; D018075:RNA, Complementary / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000187:drug effects / Q000235:genetics; D011817:Rabbits; D012964:Sodium / Q000493:pharmacokinetics / Q000494:pharmacology; D050608:Sodium-Phosphate Cotransporter Proteins; D050609:Sodium-Phosphate Cotransporter Proteins, Type I; D027981:Symporters; D014982:Xenopus laevis
D002352:Carrier Proteins; D018076:DNA, Complementary; D016376:Oligonucleotides, Antisense; D010710:Phosphates; D018075:RNA, Complementary; D012333:RNA, Messenger; C493546:SLC17A1 protein, human; D050608:Sodium-Phosphate Cotransporter Proteins; D050609:Sodium-Phosphate Cotransporter Proteins, Type I; D027981:Symporters; D012964:Sodium