PMID- 11994299
OWN - NLM
STAT- MEDLINE
DCOM- 20020812
LR  - 20220309
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 277
IP  - 28
DP  - 2002 Jul 12
TI  - The extracellular component of a transport metabolon. Extracellular loop 4 of the 
      human AE1 Cl-/HCO3- exchanger binds carbonic anhydrase IV.
PG  - 25239-46
AB  - Cytosolic carbonic anhydrase II (CAII) and the cytoplasmic C-terminal tails of 
      chloride/bicarbonate anion exchange (AE) proteins associate to form a bicarbonate 
      transport metabolon, which maximizes the bicarbonate transport rate. To determine 
      whether cell surface-anchored carbonic anhydrase IV (CAIV) interacts with AE 
      proteins to accelerate the bicarbonate transport rate, AE1-mediated bicarbonate 
      transport was monitored in transfected HEK293 cells. Expression of the inactive 
      CAII V143Y mutant blocked the interaction between endogenous cytosolic CAII and 
      AE1, AE2, and AE3 and inhibited their transport activity (53 +/- 3, 49 +/- 10, 
      and 35 +/- 1% inhibition, respectively). However, in the presence of V143Y CAII, 
      expression of CAIV restored full functional activity to AE1, AE2, and AE3 (AE1, 
      101 +/- 3; AE2, 85 +/- 5; AE3, 108 +/- 1%). In Triton X-100 extracts of 
      transfected HEK293 cells, resolved by sucrose gradient ultracentrifugation, CAIV 
      recruitment to the position of AE1 suggested a physical interaction between CAIV 
      and AE1. Gel overlay assays showed a specific interaction between CAIV and AE1, 
      AE2, and AE3. Glutathione S-transferase pull-down assays revealed that the 
      interaction between CAIV and AE1 occurs on the large fourth extracellular loop of 
      AE1. We conclude that AE1 and CAIV interact on extracellular loop 4 of AE1, 
      forming the extracellular component of a bicarbonate transport metabolon, which 
      accelerates the rate of AE-mediated bicarbonate transport.
FAU - Sterling, Deborah
AU  - Sterling D
AD  - Canadian Institutes of Health Research Membrane Protein Research Group, 
      Department of Physiology, University of Alberta, Edmonton, Canada.
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 - 20020506
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Anion Exchange Protein 1, Erythrocyte)
RN  - 0 (DNA Primers)
RN  - EC 2.5.1.18 (Glutathione Transferase)
RN  - EC 4.2.1.- (Carbonic Anhydrase IV)
SB  - IM
MH  - Amino Acid Sequence
MH  - Anion Exchange Protein 1, Erythrocyte/chemistry/*metabolism
MH  - Base Sequence
MH  - Carbonic Anhydrase IV/*metabolism
MH  - DNA Primers
MH  - Glutathione Transferase/metabolism
MH  - Humans
MH  - Molecular Sequence Data
MH  - Protein Binding
EDAT- 2002/05/08 10:00
MHDA- 2002/08/13 10:01
CRDT- 2002/05/08 10:00
PHST- 2002/05/08 10:00 [pubmed]
PHST- 2002/08/13 10:01 [medline]
PHST- 2002/05/08 10:00 [entrez]
AID - S0021-9258(19)66479-3 [pii]
AID - 10.1074/jbc.M202562200 [doi]
PST - ppublish
SO  - J Biol Chem. 2002 Jul 12;277(28):25239-46. doi: 10.1074/jbc.M202562200. Epub 2002 
      May 6.