AC   MF_01308;
DC   Protein; auto
c?   <OC:Cyanobacteriota> or <OG:Chloroplast>
TR   HAMAP; MF_01308; -; 1; level=0
XX
Names: CemA_PxcA
XX
case <OG:Chloroplast>
ID   CEMA
DE   RecName: Full=Potassium/proton antiporter CemA;
DE   AltName: Full=Chloroplast envelope membrane protein A;
DE            Short=CemA;
GN   Name=cemA;
else case <OC:Cyanobacteriota>
ID   PXCA
DE   RecName: Full=Proton extrusion protein PxcA;
GN   Name=pxcA;
end case
XX
case <OG:Chloroplast>
CC   -!- FUNCTION: Contributes to K(+)/H(+) antiport activity by supporting
CC       proton efflux to control proton extrusion and homeostasis in
CC       chloroplasts in a light-dependent manner to modulate photosynthesis.
CC       Prevents excessive induction of non-photochemical quenching (NPQ) under
CC       continuous-light conditions. Indirectly promotes efficient inorganic
CC       carbon uptake into chloroplasts.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H(+)(out) + K(+)(in) = H(+)(in) + K(+)(out);
CC         Xref=Rhea:RHEA:29467, ChEBI:CHEBI:15378, ChEBI:CHEBI:29103;
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast inner membrane; Multi-pass
CC       membrane protein.
else case <OC:Cyanobacteriota>
CC   -!- FUNCTION: Required for H(+) efflux immediately after light irradiation
CC       to form a rapid H(+) concentration gradient across the thylakoid
CC       membranes. Together with PxcL, contributes to transient H(+)
CC       uptake following dark to light transition.
CC   -!- SUBCELLULAR LOCATION: Cell inner membrane; Multi-pass membrane protein.
end case
CC   -!- SIMILARITY: Belongs to the CemA family.
XX
DR   Pfam; PF03040; CemA; 1; trigger=no
DR   General; Transmembrane; -; 2-4; trigger=yes
XX
KW   Membrane
KW   Transmembrane
case <OG:Chloroplast>
KW   Antiport
KW   Plastid inner membrane
KW   Potassium
KW   Potassium transport
else case <OC:Cyanobacteriota>
KW   Cell membrane
KW   Cell inner membrane
end case
KW   Transport
KW   Ion transport
KW   Hydrogen ion transport
KW   Transmembrane helix
XX
GO   GO:0015078; F:proton transmembrane transporter activity
GO   GO:1902600; P:proton transmembrane transport
case <OG:Chloroplast>
GO   GO:0006813; P:potassium ion transport
GO   GO:0009706; C:chloroplast inner membrane
else case <OC:Cyanobacteriota>
GO   GO:0005886; C:plasma membrane
end case
XX
FT   None
XX
Size: 226-501;
Related: None;
Template: Q37050;
Scope:
 Bacteria; Cyanobacteriota
 Plastid
Fusion:
 Nter: None
 Cter: None
Duplicate: None
Plasmid: None
Comments: The amino-terminus is very variable.
XX
# Revision 1.38 2023/10/17
//