PMID- 10198426
OWN - NLM
STAT- MEDLINE
DCOM- 19990513
LR  - 20190125
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 276
IP  - 4
DP  - 1999 Apr
TI  - Stoichiometry and Na+ binding cooperativity of rat and flounder renal type II
      Na+-Pi cotransporters.
PG  - F644-9
LID - 10.1152/ajprenal.1999.276.4.F644 [doi]
AB  - The stoichiometry of the rat and flounder isoforms of the renal type II
      sodium-phosphate (Na+-Pi) cotransporter was determined directly by simultaneous
      measurements of phosphate (Pi)-induced inward current and uptake of radiolabeled 
      Pi and Na+ in Xenopus laevis oocytes expressing the cotransporters. There was a
      direct correlation between the Pi-induced inward charge and Pi uptake into the
      oocytes; the slope indicated that one net inward charge was transported per Pi.
      There was also a direct correlation between the Pi-induced inward charge and Na+ 
      influx; the slope indicated that the influx of three Na+ ions resulted in one net
      inward charge. This behavior was similar for both isoforms. We conclude that for 
      both Na+-Pi cotransporter isoforms the Na+:Pi stoichiometry is 3:1 and that
      divalent Pi is the transported substrate. Steady-state activation of the currents
      showed that the Hill coefficients for Pi were unity for both isoforms, whereas
      for Na+, they were 1.8 (flounder) and 2.5 (rat). Therefore, despite significant
      differences in the apparent Na+ binding cooperativity, the estimated Na+:Pi
      stoichiometry was the same for both isoforms.
FAU - Forster, I C
AU  - Forster IC
AD  - Physiologisches Institut, Universitat Zurich, CH-8057 Zurich, Switzerland.
      forster@physiol.unizh.ch
FAU - Loo, D D
AU  - Loo DD
FAU - Eskandari, S
AU  - Eskandari S
LA  - eng
GR  - DK-19567/DK/NIDDK NIH HHS/United States
GR  - NS-25554/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 0 (Carrier Proteins)
RN  - 0 (Sodium-Phosphate Cotransporter Proteins)
RN  - 0 (Sodium-Phosphate Cotransporter Proteins, Type II)
RN  - 0 (Symporters)
RN  - 9NEZ333N27 (Sodium)
SB  - IM
MH  - Animals
MH  - Carrier Proteins/*metabolism
MH  - Chemical Phenomena
MH  - Chemistry
MH  - Electrochemistry
MH  - Female
MH  - Flounder
MH  - Homeostasis
MH  - Hydrogen-Ion Concentration
MH  - Kidney/*metabolism
MH  - Kinetics
MH  - Mathematics
MH  - Oocytes/metabolism
MH  - Rats
MH  - Sodium/*metabolism
MH  - Sodium-Phosphate Cotransporter Proteins
MH  - Sodium-Phosphate Cotransporter Proteins, Type II
MH  - *Symporters
MH  - Xenopus laevis
EDAT- 1999/04/13 00:00
MHDA- 1999/04/13 00:01
CRDT- 1999/04/13 00:00
PHST- 1999/04/13 00:00 [pubmed]
PHST- 1999/04/13 00:01 [medline]
PHST- 1999/04/13 00:00 [entrez]
AID - 10.1152/ajprenal.1999.276.4.F644 [doi]
PST - ppublish
SO  - Am J Physiol. 1999 Apr;276(4):F644-9. doi: 10.1152/ajprenal.1999.276.4.F644.