PMID- 23878365
OWN - NLM
STAT- MEDLINE
DCOM- 20140620
LR  - 20211021
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Print)
IS  - 0022-3751 (Linking)
VI  - 591
IP  - 20
DP  - 2013 Oct 15
TI  - Activity and distribution of intracellular carbonic anhydrase II and their 
      effects on the transport activity of anion exchanger AE1/SLC4A1.
PG  - 4963-82
LID - 10.1113/jphysiol.2013.251181 [doi]
AB  - We have investigated the previously published 'metabolon hypothesis' postulating 
      that a close association of the anion exchanger 1 (AE1) and cytosolic carbonic 
      anhydrase II (CAII) exists that greatly increases the transport activity of AE1. 
      We study whether there is a physical association of and direct functional 
      interaction between CAII and AE1 in the native human red cell and in tsA201 cells 
      coexpressing heterologous fluorescent fusion proteins CAII-CyPet and YPet-AE1. In 
      these doubly transfected tsA201 cells, YPet-AE1 is clearly associated with the 
      cell membrane, whereas CAII-CyPet is homogeneously distributed throughout the 
      cell in a cytoplasmic pattern. Forster resonance energy transfer measurements 
      fail to detect close proximity of YPet-AE1 and CAII-CyPet. The absence of an 
      association of AE1 and CAII is supported by immunoprecipitation experiments using 
      Flag-antibody against Flag-tagged AE1 expressed in tsA201 cells, which does not 
      co-precipitate native CAII but co-precipitates coexpressed ankyrin. Both the CAII 
      and the AE1 fusion proteins are fully functional in tsA201 cells as judged by CA 
      activity and by cellular HCO3(-) permeability (P(HCO3(-))) sensitive to 
      inhibition by 4,4-Diisothiocyano-2,2-stilbenedisulfonic acid. Expression of the 
      non-catalytic CAII mutant V143Y leads to a drastic reduction of endogenous CAII 
      and to a corresponding reduction of total intracellular CA activity. 
      Overexpression of an N-terminally truncated CAII lacking the proposed site of 
      interaction with the C-terminal cytoplasmic tail of AE1 substantially increases 
      intracellular CA activity, as does overexpression of wild-type CAII. These 
      variously co-transfected tsA201 cells exhibit a positive correlation between 
      cellular P(HCO3(-)) and intracellular CA activity. The relationship reflects that 
      expected from changes in cytoplasmic CA activity improving substrate supply to or 
      removal from AE1, without requirement for a CAII-AE1 metabolon involving physical 
      interaction. A functional contribution of the hypothesized CAII-AE1 metabolon to 
      erythroid AE1-mediated HCO3(-) transport was further tested in normal red cells 
      and red cells from CAII-deficient patients that retain substantial CA activity 
      associated with the erythroid CAI protein lacking the proposed AE1-binding 
      sequence. Erythroid P(HCO3(-)) was indistinguishable in these two cell types, 
      providing no support for the proposed functional importance of the physical 
      interaction of CAII and AE1. A theoretical model predicts that homogeneous 
      cytoplasmic distribution of CAII is more favourable for cellular transport of 
      HCO3(-) and CO2 than is association of CAII with the cytoplasmic surface of the 
      plasma membrane. This is due to the fact that the relatively slow intracellular 
      transport of H(+) makes it most efficient to place the CA in the vicinity of the 
      haemoglobin molecules, which are homogeneously distributed over the cytoplasm.
FAU - Al-Samir, Samer
AU  - Al-Samir S
AD  - G. Gros: Zentrum Physiologie, Vegetative Physiologie 4220, Medizinische 
      Hochschule Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany. 
      Gros.Gerolf@MH-Hannover.de; V. Endeward: Zentrum Physiologie 4220, Medizinische 
      Hochschule Hannover, Germany.  Endeward.Volker@MH-Hannover.de.
FAU - Papadopoulos, Symeon
AU  - Papadopoulos S
FAU - Scheibe, Renate J
AU  - Scheibe RJ
FAU - Meissner, Joachim D
AU  - Meissner JD
FAU - Cartron, Jean-Pierre
AU  - Cartron JP
FAU - Sly, William S
AU  - Sly WS
FAU - Alper, Seth L
AU  - Alper SL
FAU - Gros, Gerolf
AU  - Gros G
FAU - Endeward, Volker
AU  - Endeward V
LA  - eng
GR  - UL1 RR025758/RR/NCRR NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20130722
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
RN  - 0 (Anion Exchange Protein 1, Erythrocyte)
RN  - 0 (Ankyrins)
RN  - 0 (SLC4A1 protein, human)
RN  - EC 4.2.1.- (Carbonic Anhydrase II)
SB  - IM
MH  - Anion Exchange Protein 1, Erythrocyte/genetics/*metabolism
MH  - Ankyrins/metabolism
MH  - Carbonic Anhydrase II/genetics/*metabolism
MH  - Cytoplasm/metabolism
MH  - HEK293 Cells
MH  - Humans
MH  - Ion Transport
MH  - Models, Biological
MH  - Protein Binding
MH  - Protein Transport
PMC - PMC3810803
EDAT- 2013/07/24 06:00
MHDA- 2014/06/21 06:00
PMCR- 2014/10/15
CRDT- 2013/07/24 06:00
PHST- 2013/07/24 06:00 [entrez]
PHST- 2013/07/24 06:00 [pubmed]
PHST- 2014/06/21 06:00 [medline]
PHST- 2014/10/15 00:00 [pmc-release]
AID - jphysiol.2013.251181 [pii]
AID - 10.1113/jphysiol.2013.251181 [doi]
PST - ppublish
SO  - J Physiol. 2013 Oct 15;591(20):4963-82. doi: 10.1113/jphysiol.2013.251181. Epub 
      2013 Jul 22.