AC   MF_01128;
DC   Protein; auto
TR   HAMAP; MF_01128; -; 1; level=0
XX
Names: CLC_ClcA
XX
ID   CLCA
DE   RecName: Full=H(+)/Cl(-) exchange transporter ClcA;
case <OC:Enterobacterales>
GN   Name=clcA; Synonyms=eriC;
else
GN   Name=clcA;
end case
XX
CC   -!- FUNCTION: Proton-coupled chloride transporter. Functions as antiport
CC       system and exchanges two chloride ions for 1 proton. Probably acts as
CC       an electrical shunt for an outwardly-directed proton pump that is
CC       linked to amino acid decarboxylation, as part of the extreme acid
CC       resistance (XAR) response.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2 chloride(in) + H(+)(out) = 2 chloride(out) + H(+)(in);
CC         Xref=Rhea:RHEA:29567, ChEBI:CHEBI:15378, ChEBI:CHEBI:17996;
CC   -!- SUBUNIT: Homodimer.
case not defined <Property:Membrane> or <Property:Membrane=1>
CC   -!- SUBCELLULAR LOCATION: Cell membrane; Multi-pass membrane protein.
else case <Property:Membrane=2>
CC   -!- SUBCELLULAR LOCATION: Cell inner membrane; Multi-pass membrane protein.
end case
CC   -!- SIMILARITY: Belongs to the chloride channel (TC 2.A.49) family. ClcA
CC       subfamily.
XX
DR   Pfam; PF00654; Voltage_CLC; 1; trigger=no
DR   PRINTS; PR00762; CLCHANNEL; 1; trigger=no
case not defined <Property:Membrane> or <Property:Membrane=1>
DR   General; Transmembrane; -; 11; trigger=yes
end case
XX
KW   Antiport
case defined <Property:Membrane> and <Property:Membrane=2>
KW   Cell inner membrane
end case
KW   Cell membrane
KW   Chloride
KW   Ion transport
KW   Membrane
KW   Transmembrane
KW   Transport
KW   Transmembrane helix
XX
GO   GO:0015297; F:antiporter activity
GO   GO:0006821; P:chloride transport
GO   GO:0005886; C:plasma membrane
XX
FT   From: CLCA_ECOLI (P37019)
case defined <Property:Membrane> and <Property:Membrane=2>
FT   TOPO_DOM        Nter..32
FT                   /note="Cytoplasmic"
FT   TRANSMEM        33..69
FT                   /note="Helical"
FT   TOPO_DOM        70..76
FT                   /note="Periplasmic"
FT   TRANSMEM        77..100
FT                   /note="Helical"
FT   INTRAMEM        109..116
FT                   /note="Helical"
FT   TOPO_DOM        117..123
FT                   /note="Cytoplasmic"
FT   TRANSMEM        124..141
FT                   /note="Helical"
FT   TRANSMEM        148..166
FT                   /note="Helical"
FT   TOPO_DOM        167..176
FT                   /note="Cytoplasmic"
FT   INTRAMEM        177..189
FT                   /note="Helical"
FT   INTRAMEM        193..201
FT                   /note="Helical"
FT   TOPO_DOM        202..214
FT                   /note="Cytoplasmic"
FT   TRANSMEM        215..232
FT                   /note="Helical"
FT   TOPO_DOM        233..252
FT                   /note="Periplasmic"
FT   TRANSMEM        253..281
FT                   /note="Helical"
FT   TOPO_DOM        282..287
FT                   /note="Cytoplasmic"
FT   TRANSMEM        288..309
FT                   /note="Helical"
FT   TOPO_DOM        310..329
FT                   /note="Periplasmic"
FT   TRANSMEM        330..349
FT                   /note="Helical"
FT   TRANSMEM        355..376
FT                   /note="Helical"
FT   TOPO_DOM        377..386
FT                   /note="Periplasmic"
FT   INTRAMEM        387..401
FT                   /note="Helical"
FT   INTRAMEM        402..404
FT                   /note="Note=Loop between two helices"
FT   INTRAMEM        405..416
FT                   /note="Helical"
FT   INTRAMEM        417..421
FT                   /note="Note=Loop between two helices"
FT   TRANSMEM        422..438
FT                   /note="Helical"
FT   TOPO_DOM        439..Cter
FT                   /note="Cytoplasmic"
FT   MOTIF           106..110
FT                   /note="Selectivity filter part_1"
FT   MOTIF           146..150
FT                   /note="Selectivity filter part_2"
FT   MOTIF           355..359
FT                   /note="Selectivity filter part_3"
end case
FT   BINDING         107
FT                   /ligand="chloride"
FT                   /ligand_id="ChEBI:CHEBI:17996"
FT   Condition: S
FT   BINDING         356
FT                   /ligand="chloride"
FT                   /ligand_id="ChEBI:CHEBI:17996"
FT   Condition: I
FT   BINDING         357
FT                   /ligand="chloride"
FT                   /ligand_id="ChEBI:CHEBI:17996"
FT   Condition: F
FT   BINDING         445
FT                   /ligand="chloride"
FT                   /ligand_id="ChEBI:CHEBI:17996"
FT   Condition: Y
FT   SITE            148
FT                   /note="Mediates proton transfer from the outer aqueous
FT                   phase to the interior of the protein; involved in linking
FT                   H(+) and Cl(-) transport"
FT   Condition: E
FT   SITE            203
FT                   /note="Mediates proton transfer from the protein to the
FT                   inner aqueous phase"
FT   Condition: E
XX
Size: 467-478;
Related: None;
Template: P37019;
Scope:
 Bacteria
Fusion:
 Nter: None
 Cter: None
Duplicate: None
Plasmid: None
Comments: ClcA from E.coli was originally characterized as a voltage-gated chloride
 channel. It has now become clear that it is, in fact, a transporter. E.coli
 has at least one paralog, ClcB, and maybe YfeO, for which there is no
 electrophysiological characterization - they may or may not be transporters
 too. This family of proteins with high similarity to ClcA have, therefore,
 been considered as transporters as well. Further characterization is needed
 to distinguish ion channels from transporters, as it seems that the structural
 boundary separating channels and transporters is not as clear-cut as generally
 thought.
XX
# Revision 1.37 2022/11/19
//