Protein: K(+) efflux antiporter 2, chloroplastic (AtKEA2) (O65272)
Organism: Arabidopsis thaliana (Mouse-ear cress)
Function: Electroneutral K(+)/H(+) efflux antiporter modulating monovalent cation and pH homeostasis in plastids, especially during plastid division and thylakoid membrane formation. Transports K(+) and Cs(+) preferentially relative to Na(+) or Li(+). May function in osmotic adjustment. Collaboratively with KEA1, adjusts alkaline stromal pH upon light to dark transitions in plastids. Together with KEA1, critical for chloroplast development, including chloroplast RNA-metabolism (e.g. rRNA maturation, polysome loading and RNA-protein interactions) and plastid gene expression (PGE), ion homeostasis, and photosynthesis. Contributes, during early seedling development, to the regulation of photosynthesis and abscisic acid- (ABA-) mediated primary root growth in a sucrose-dependent manner. Involved in the regulation of reactive oxygen and nitrogen species (ROS and RNS) metabolism. Required in roots for rapid hyperosmotic-induced Ca(2+) responses and for osmo-sensory potentiation in hyperosmotic conditions. May counteract resilience to drought and salt stress, involving photorespiratory pathway and stomata closure.
Subcellular location: Plastid, chloroplast inner membrane {ECO:0000269|PubMed:18431481, ECO:0000269|PubMed:22551943, ECO:0000269|PubMed:24794527, ECO:0000269|PubMed:33485149}; Multi-pass membrane protein {ECO:0000255}. Plastid inner membrane {ECO:0000269|PubMed:33485149}; Multi-pass membrane protein {ECO:0000255}. Note=Specifically localized to the two caps of the dividing organelle separated by the fission plane (at protein level) (PubMed:27443603). Present both in photosynthetic chloroplasts of shoots and in non-photosynthetic plastids in roots (PubMed:33485149). {ECO:0000269|PubMed:27443603, ECO:0000269|PubMed:33485149}.
Interaction partners:
- Sodium/proton antiporter 1
- F-actin-capping protein subunit alpha
- Cation/H
- Cation/H
- Two-pore potassium channel 3
- Cation/H
- Cation/H
- Potassium transporter 10
- Cation/H
- Sodium/hydrogen exchanger 7
Sequence:
MDFASSVQRQSMFHGGADFASYCLPNRMISAKLCPKGLGGTRFWDPMIDSKVRSAIRSKRNVSYRSSLTLNADFNGRFYGHLLPAKPQNVPLGFRLLCQSSDSVGDLVGNDRNLEFAEGSDDREVTFSKEEKDTREQDSAPSLEELRDLLNKATKELEVASLNSTMFEEKAQRISEVAIALKDEAASAWNDVNQTLNVVQEAVDEESVAKEAVQKATMALSLAEARLQVALESLEAEGYNTSEESEVRDGVKDKEEALLSAKADIKECQENLASCEEQLRRLQVKKDELQKEVDRLNEAAERAQISALKAEEDVANIMVLAEQAVAFELEATQRVNDAEIALQRAEKTLFGSQTQETTQGKVLDGKNTIVGEDEVLSEIVDVSHQAERDLVVVGVSSDVGTQSYESDNENGKPTADFAKEAEGEAEKSKNVVLTKKQEVQKDLPRESSSHNGTKTSLKKSSRFFPASFFSSNGDGTATVFESLVESAKQQWPKLILGFTLLGAGVAIYSNGVGRNNQLPQQPNIVSTSAEDVSSSTKPLIRQMQKLPKRIKKLLEMFPQQEVNEEEASLLDVLWLLLASVIFVPLFQKIPGGSPVLGYLAAGILIGPYGLSIIRNVHGTKAIAEFGVVFLLFNIGLELSVERLSSMKKYVFGLGSAQVLVTAAVIGLITHYVAGQAGPAAIVIGNGLALSSTAVVLQVLQERGESTSRHGRATFSVLLFQDLAVVVLLILIPLISPNSSKGGIGFQAIAEALGLAAIKAAVAITGIIAGGRLLLRPIYKQIAENRNAEIFSANTLLVILGTSLLTARAGLSMALGAFLAGLLLAETEFSLQVESDIAPYRGLLLGLFFMTVGMSIDPKLLLANFPLIMGTLGLLLVGKTILVVIIGKLFGISIISAVRVGLLLAPGGEFAFVAFGEAVNQGIMTPQLSSLLFLVVGISMALTPWLAAGGQLIASRFELQDVRSLLPVESETDDLQGHIIICGFGRIGQIIAQLLSERLIPFVALDVSSDRVAIGRSLDLPVYFGDAGSREVLHKIGADRACAAAIALDTPGANYRCVWALSKYFPNVKTFVRAHDVDHGLNLEKAGATAVVPETLEPSLQLAAAVLAQAKLPTSEIATTINEFRSRHLSELAELCEASGSSLGYGFSRSTSKPKPPSPSETSDDNQIIEGTLAI