Molecular Cloning and Hormonal Regulation of PiT-1, a Sodium-Dependent Phosphate Cotransporter from Rat Parathyroid Glands

Abstract The extracellular concentration of inorganic phosphate (Pi) is an important determinant of parathyroid cell function. The effects of Pi may be mediated through specific molecules in the parathyroid cell membrane, one candidate molecule for which would be a Na+-dependent Pi cotransporter. A...

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Bibliographic Details
Published in:Endocrinology (Philadelphia) 1998-04, Vol.139 (4), p.1692-1699
Main Authors: Tatsumi, Sawako, Segawa, Hiroko, Morita, Kyoko, Haga, Hiromi, Kouda, Tomoko, Yamamoto, Hironori, Inoue, Yoshio, Nii, Tomoko, Katai, Kanako, Taketani, Yutaka, Miyamoto, Ken-ichi, Takeda, Eiji
Format: Article
Language:English
Subjects:
Amino acid sequence
Amino acids
Animal tissues
Calciferol
Calcitriol
Cell membranes
Cloning
Complementary DNA
Deoxyribonucleic acid
Diet
DNA
Gametocytes
Gene expression
Intestine
mRNA
Nucleotide sequence
Nutrient deficiency
Oocytes
Parathyroid
Pit1 protein
Small intestine
Sodium
Vitamin D
Vitamin D3
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Summary:Abstract The extracellular concentration of inorganic phosphate (Pi) is an important determinant of parathyroid cell function. The effects of Pi may be mediated through specific molecules in the parathyroid cell membrane, one candidate molecule for which would be a Na+-dependent Pi cotransporter. A complementary DNA encoding a Na+-Pi cotransporter, termed rat PiT-1, has now been isolated from rat parathyroid. The 2890-bp complementary DNA encodes a protein of 681 amino acids that shows sequence identities of 97% and 93% with the type III Na+-Pi cotransporters mouse PiT-1 and human PiT-1, respectively. Expression of rat PiT-1 in Xenopus oocytes revealed that it possesses Na+-dependent Pi cotransport activity. PiT-1 messenger RNA (mRNA) is widely distributed in rat tissues and is most abundant in brain, bone, and small intestine. The amount of PiT-1 mRNA in the parathyroid of vitamin D-deficent rats was reduced compared with that in normal animals and increased markedly after administration of 1,25-dihydroxyvitamin D3. Furthermore, the abundance of PiT-1 mRNA in the parathyroid was much greater in rats fed a low-Pi diet than in those fed a high-Pi diet. Thus, rat PiT-1 may contribute to the effects of Pi and vitamin D on parathyroid function.
ISSN:0013-7227
1945-7170
DOI:10.1210/endo.139.4.5925