HAMAP

Accession	MF_01128
Dates	22-APR-2003 (Created) 12-JUL-2010 (Last updated, Version 31)

Data class

Protein

Predictors

HAMAP; MF_01128; [distribution of match scores in UniProtKB];[seed alignment for MF_01128]

Names

CLC_ClcA

Identifier

CLCA

Protein name

RecName: Full=H(+)/Cl(-) exchange transporter ClcA;

Gene name

clcA, eriC

Gene name

clcA

FUNCTION: Proton-coupled chloride transporter. Functions as antiport system and exchanges two chloride ions for 1 proton. Probably acts as an electrical shunt for an outwardly-directed proton pump that is linked to amino acid decarboxylation, as part of the extreme acid resistance (XAR) response (By similarity).

SUBUNIT: Homodimer (By similarity).

SUBCELLULAR LOCATION: Cell membrane; Multi-pass membrane protein (By similarity).

SUBCELLULAR LOCATION: Cell inner membrane; Multi-pass membrane protein (By similarity).

SIMILARITY: Belongs to the chloride channel (TC 2.A.49) family. ClcA subfamily.

Pfam	PF00654; Voltage_CLC; 1;
PRINTS	PR00762; CLCHANNEL; 1;

General

Transmembrane; -; 11; trigger=Yes;

Antiport.

Cell inner membrane.

Cell membrane, Chloride, Ion transport, Membrane, Transmembrane, Transport, Transmembrane helix.

GO:0015297; Molecular function: antiporter activity.
GO:0006821; Biological process: chloride transport.
GO:0005886; Cellular component: plasma membrane.

From: CLCA_ECOLI (P37019)
Key		From		To		Description		Condition		FTGroup
TOPO_DOM		Nter		32		Cytoplasmic (By similarity)
TRANSMEM		33		69		Helical (By similarity)
TOPO_DOM		70		76		Periplasmic (By similarity)
TRANSMEM		77		100		Helical (By similarity)
INTRAMEM		109		116		Helical (By similarity)
TOPO_DOM		117		123		Cytoplasmic (By similarity)
TRANSMEM		124		141		Helical (By similarity)
TRANSMEM		148		166		Helical (By similarity)
TOPO_DOM		167		176		Cytoplasmic (By similarity)
INTRAMEM		177		189		Helical (By similarity)
INTRAMEM		193		201		Helical (By similarity)
TOPO_DOM		202		214		Cytoplasmic (By similarity)
TRANSMEM		215		232		Helical (By similarity)
TOPO_DOM		233		252		Periplasmic (By similarity)
TRANSMEM		253		281		Helical (By similarity)
TOPO_DOM		282		287		Cytoplasmic (By similarity)
TRANSMEM		288		309		Helical (By similarity)
TOPO_DOM		310		329		Periplasmic (By similarity)
TRANSMEM		330		349		Helical (By similarity)
TRANSMEM		355		376		Helical (By similarity)
TOPO_DOM		377		386		Periplasmic (By similarity)
INTRAMEM		387		401		Helical (By similarity)
INTRAMEM		402		404		Note=Loop between two helices (By similarity)
INTRAMEM		405		416		Helical (By similarity)
INTRAMEM		417		421		Note=Loop between two helices (By similarity)
TRANSMEM		422		438		Helical (By similarity)
TOPO_DOM		439		Cter		Cytoplasmic (By similarity)
MOTIF		106		110		Selectivity filter part_1 (By similarity)
MOTIF		146		150		Selectivity filter part_2 (By similarity)
MOTIF		355		359		Selectivity filter part_3 (By similarity)

Key		From		To		Description		Condition		FTGroup
BINDING		107		107		Chloride (By similarity)		S
BINDING		356		356		Chloride; via amide nitrogen (By similarity)		I
BINDING		357		357		Chloride; via amide nitrogen (By similarity)		F
BINDING		445		445		Chloride (By similarity)		Y
SITE		148		148		Mediates proton transfer from the outer aqueous phase to the interior of the protein; involved in linking H(+) and Cl(-) transport (By similarity)		E
SITE		203		203		Mediates proton transfer from the protein to the inner aqueous phase (By similarity)		E

Size range:	467-478 amino acids
Related UniRules:	None
Template:	P37019 (CLCA_ECOLI)
Scope:	Bacteria
Fusion:	Nter: None; Cter: None
Duplicate:	None
Plasmid encoded:	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.