PMID- 14736710
OWN - NLM
STAT- MEDLINE
DCOM- 20040714
LR  - 20200930
IS  - 0363-6143 (Print)
IS  - 0363-6143 (Linking)
VI  - 286
IP  - 6
DP  - 2004 Jun
TI  - Regulation of the human NBC3 Na+/HCO3- cotransporter by carbonic anhydrase II and 
      PKA.
PG  - C1423-33
AB  - Human NBC3 is an electroneutral Na(+)/HCO(3)(-) cotransporter expressed in heart, 
      skeletal muscle, and kidney in which it plays an important role in HCO(3)(-) 
      metabolism. Cytosolic enzyme carbonic anhydrase II (CAII) catalyzes the reaction 
      CO(2) + H(2)O left arrow over right arrow HCO(3)(-) + H(+) in many tissues. We 
      investigated whether NBC3, like some Cl(-)/HCO(3)(-) exchange proteins, could 
      bind CAII and whether PKA could regulate NBC3 activity through modulation of CAII 
      binding. CAII bound the COOH-terminal domain of NBC3 (NBC3Ct) with K(d) = 101 nM; 
      the interaction was stronger at acid pH. Cotransfection of HEK-293 cells with 
      NBC3 and CAII recruited CAII to the plasma membrane. Mutagenesis of consensus 
      CAII binding sites revealed that the D1135-D1136 region of NBC3 is essential for 
      CAII/NBC3 interaction and for optimal function, because the NBC3 D1135N/D1136N 
      retained only 29 +/- 22% of wild-type activity. Coexpression of the functionally 
      dominant-negative CAII mutant V143Y with NBC3 or addition of 100 microM 
      8-bromoadenosine to NBC3 transfected cells reduced intracellular pH (pH(i)) 
      recovery rate by 31 +/- 3, or 38 +/- 7%, respectively, relative to untreated NBC3 
      transfected cells. The effects were additive, together decreasing the pH(i) 
      recovery rate by 69 +/- 12%, suggesting that PKA reduces transport activity by a 
      mechanism independently of CAII. Measurements of PKA-dependent phosphorylation by 
      mass spectroscopy and labeling with [gamma-(32)P]ATP showed that NBC3Ct was not a 
      PKA substrate. These results demonstrate that NBC3 and CAII interact to maximize 
      the HCO(3)(-) transport rate. Although PKA decreased NBC3 transport activity, it 
      did so independently of the NBC3/CAII interaction and did not involve 
      phosphorylation of NBC3Ct.
FAU - Loiselle, Frederick B
AU  - Loiselle FB
AD  - Canadian Institute of Health Research Membrane Protein Research Group, Department 
      of Physiology, University of Alberta, Edmonton, Canada T6G 2H7.
FAU - Morgan, Patricio E
AU  - Morgan PE
FAU - Alvarez, Bernardo V
AU  - Alvarez BV
FAU - Casey, Joseph R
AU  - Casey JR
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20040121
PL  - United States
TA  - Am J Physiol Cell Physiol
JT  - American journal of physiology. Cell physiology
JID - 100901225
RN  - 0 (SLC4A7 protein, human)
RN  - 0 (Sodium-Bicarbonate Symporters)
RN  - 2946-39-6 (8-bromoadenosine)
RN  - EC 2.7.11.11 (Cyclic AMP-Dependent Protein Kinases)
RN  - EC 4.2.1.- (Carbonic Anhydrase II)
RN  - K72T3FS567 (Adenosine)
SB  - IM
MH  - Acid-Base Equilibrium/drug effects/*physiology
MH  - Adenosine/*analogs & derivatives/pharmacology
MH  - Binding Sites/drug effects/physiology
MH  - Carbonic Anhydrase II/genetics/*metabolism
MH  - Cell Line
MH  - Cell Membrane/*enzymology
MH  - Cyclic AMP-Dependent Protein Kinases/genetics/*metabolism
MH  - Cytoplasm/drug effects/metabolism
MH  - Epithelial Cells/*enzymology
MH  - Humans
MH  - Mutation/genetics
MH  - Phosphorylation/drug effects
MH  - Protein Binding/drug effects/physiology
MH  - Protein Structure, Tertiary/drug effects/physiology
MH  - Protein Transport/drug effects/physiology
MH  - Sodium-Bicarbonate Symporters/genetics/*metabolism
MH  - Transfection
EDAT- 2004/01/23 05:00
MHDA- 2004/07/15 05:00
CRDT- 2004/01/23 05:00
PHST- 2004/01/23 05:00 [pubmed]
PHST- 2004/07/15 05:00 [medline]
PHST- 2004/01/23 05:00 [entrez]
AID - 00382.2003 [pii]
AID - 10.1152/ajpcell.00382.2003 [doi]
PST - ppublish
SO  - Am J Physiol Cell Physiol. 2004 Jun;286(6):C1423-33. doi: 
      10.1152/ajpcell.00382.2003. Epub 2004 Jan 21.