ID KTRB_VIBAL Reviewed; 455 AA. AC O87953; DT 03-SEP-2014, integrated into UniProtKB/Swiss-Prot. DT 01-NOV-1998, sequence version 1. DT 02-DEC-2020, entry version 46. DE RecName: Full=Ktr system potassium uptake protein B; DE Short=K(+)-uptake protein KtrB; GN Name=ktrB; OS Vibrio alginolyticus. OC Bacteria; Proteobacteria; Gammaproteobacteria; Vibrionales; Vibrionaceae; OC Vibrio. OX NCBI_TaxID=663; RN [1] RP NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION, AND GENE NAME. RX PubMed=9642210; DOI=10.1128/jb.180.13.3491-3494.1998; RA Nakamura T., Yuda R., Unemoto T., Bakker E.P.; RT "KtrAB, a new type of bacterial K(+)-uptake system from Vibrio RT alginolyticus."; RL J. Bacteriol. 180:3491-3494(1998). RN [2] RP FUNCTION, ACTIVITY REGULATION, SUBCELLULAR LOCATION, DOMAIN, AND RP MUTAGENESIS OF GLY-290. RX PubMed=10359077; DOI=10.1016/s0014-5793(99)00504-9; RA Tholema N., Bakker E.P., Suzuki A., Nakamura T.; RT "Change to alanine of one out of four selectivity filter glycines in KtrB RT causes a two orders of magnitude decrease in the affinities for both K+ and RT Na+ of the Na+ dependent K+ uptake system KtrAB from Vibrio RT alginolyticus."; RL FEBS Lett. 450:217-220(1999). RN [3] RP FUNCTION, BIOPHYSICOCHEMICAL PROPERTIES, SUBUNIT, SUBCELLULAR LOCATION, RP DOMAIN, AND MUTAGENESIS OF GLY-70; GLY-185; GLY-290 AND GLY-402. RX PubMed=16210320; DOI=10.1074/jbc.m507647200; RA Tholema N., Vor der Brueggen M., Maeser P., Nakamura T., Schroeder J.I., RA Kobayashi H., Uozumi N., Bakker E.P.; RT "All four putative selectivity filter glycine residues in KtrB are RT essential for high affinity and selective K+ uptake by the KtrAB system RT from Vibrio alginolyticus."; RL J. Biol. Chem. 280:41146-41154(2005). RN [4] RP SUBUNIT. RX PubMed=17344221; DOI=10.1074/jbc.m609084200; RA Kroening N., Willenborg M., Tholema N., Haenelt I., Schmid R., Bakker E.P.; RT "ATP binding to the KTN/RCK subunit KtrA from the K+ -uptake system KtrAB RT of Vibrio alginolyticus: its role in the formation of the KtrAB complex and RT its requirement in vivo."; RL J. Biol. Chem. 282:14018-14027(2007). RN [5] RP SUBUNIT, SUBCELLULAR LOCATION, AND MUTAGENESIS OF GLY-314; GLY-316; RP SER-317; THR-318; THR-320; GLY-321; GLY-322; GLY-323; ILE-324; LYS-325; RP VAL-326; SER-327 AND 326-VAL--THR-328. RX PubMed=20097755; DOI=10.1074/jbc.m109.089870; RA Haenelt I., Loechte S., Sundermann L., Elbers K., Vor der Brueggen M., RA Bakker E.P.; RT "Gain of function mutations in membrane region M2C2 of KtrB open a gate RT controlling K+ transport by the KtrAB system from Vibrio alginolyticus."; RL J. Biol. Chem. 285:10318-10327(2010). CC -!- FUNCTION: Part of the Na(+)-dependent high affinity K(+) uptake system CC KtrAB. KtrB is the K(+)-translocating subunit. CC {ECO:0000269|PubMed:10359077, ECO:0000269|PubMed:16210320, CC ECO:0000269|PubMed:9642210}. CC -!- ACTIVITY REGULATION: K(+) transport is stimulated by Na(+). CC {ECO:0000269|PubMed:10359077}. CC -!- BIOPHYSICOCHEMICAL PROPERTIES: CC Kinetic parameters: CC KM=0.025 mM for K(+) {ECO:0000269|PubMed:16210320}; CC KM=6 mM for Na(+) {ECO:0000269|PubMed:16210320}; CC Vmax=200 nmol/min/mg enzyme with K(+) as substrate CC {ECO:0000269|PubMed:16210320}; CC Vmax=110 nmol/min/mg enzyme with Na(+) as substrate CC {ECO:0000269|PubMed:16210320}; CC -!- SUBUNIT: The uptake system is composed of KtrA and KtrB. CC {ECO:0000269|PubMed:16210320, ECO:0000269|PubMed:17344221, CC ECO:0000269|PubMed:20097755}. CC -!- SUBCELLULAR LOCATION: Cell inner membrane {ECO:0000269|PubMed:10359077, CC ECO:0000269|PubMed:16210320, ECO:0000269|PubMed:20097755}; Multi-pass CC membrane protein {ECO:0000269|PubMed:10359077, CC ECO:0000269|PubMed:16210320, ECO:0000269|PubMed:20097755}. CC -!- DOMAIN: Contains four repeated domains, each composed of two CC transmembrane helices connected by a putative pore loop (p-loop). Four CC conserved glycine residues in the p-loops are part of a selectivity CC filter for K(+) ions. {ECO:0000269|PubMed:10359077, CC ECO:0000269|PubMed:16210320}. CC -!- MISCELLANEOUS: KtrB alone mediates slow Na(+)-independent K(+) uptake, CC as well as K(+)-independent Na(+) uptake. CC {ECO:0000305|PubMed:20097755}. CC -!- SIMILARITY: Belongs to the TrkH potassium transport family. Ktr (TC CC 2.A.38.4) subfamily. {ECO:0000305}. CC --------------------------------------------------------------------------- CC Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms CC Distributed under the Creative Commons Attribution (CC BY 4.0) License CC --------------------------------------------------------------------------- DR EMBL; D89592; BAA32063.1; -; Genomic_DNA. DR STRING; 1219076.N646_3056; -. DR TCDB; 2.A.38.4.2; the k(+) transporter (trk) family. DR eggNOG; COG0168; Bacteria. DR GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW. DR GO; GO:0005886; C:plasma membrane; IEA:UniProtKB-SubCell. DR GO; GO:0015379; F:potassium:chloride symporter activity; IEA:InterPro. DR InterPro; IPR003445; Cat_transpt. DR InterPro; IPR004772; TrkH. DR Pfam; PF02386; TrkH; 1. DR TIGRFAMs; TIGR00933; 2a38; 1. PE 1: Evidence at protein level; KW Cell inner membrane; Cell membrane; Ion transport; Membrane; Potassium; KW Potassium transport; Transmembrane; Transmembrane helix; Transport. FT CHAIN 1..455 FT /note="Ktr system potassium uptake protein B" FT /id="PRO_0000430033" FT TRANSMEM 27..47 FT /note="Helical" FT /evidence="ECO:0000255" FT INTRAMEM 54..74 FT /evidence="ECO:0000255" FT TRANSMEM 86..106 FT /note="Helical" FT /evidence="ECO:0000255" FT TRANSMEM 141..161 FT /note="Helical" FT /evidence="ECO:0000255" FT INTRAMEM 169..189 FT /evidence="ECO:0000255" FT TRANSMEM 201..221 FT /note="Helical" FT /evidence="ECO:0000255" FT TRANSMEM 240..260 FT /note="Helical" FT /evidence="ECO:0000255" FT INTRAMEM 291..313 FT /evidence="ECO:0000255" FT TRANSMEM 318..340 FT /note="Helical" FT /evidence="ECO:0000255" FT TRANSMEM 362..382 FT /note="Helical" FT /evidence="ECO:0000255" FT INTRAMEM 390..410 FT /evidence="ECO:0000255" FT TRANSMEM 418..438 FT /note="Helical" FT /evidence="ECO:0000255" FT MUTAGEN 70 FT /note="G->A,S: Decrease in K(+) uptake activity." FT /evidence="ECO:0000269|PubMed:16210320" FT MUTAGEN 70 FT /note="G->D: Exhibits very low K(+) uptake activity." FT /evidence="ECO:0000269|PubMed:16210320" FT MUTAGEN 185 FT /note="G->A,D: Decrease in K(+) uptake activity." FT /evidence="ECO:0000269|PubMed:16210320" FT MUTAGEN 185 FT /note="G->S: Exhibits very low K(+) uptake activity." FT /evidence="ECO:0000269|PubMed:16210320" FT MUTAGEN 290 FT /note="G->A: Decrease in K(+) uptake activity." FT /evidence="ECO:0000269|PubMed:10359077, FT ECO:0000269|PubMed:16210320" FT MUTAGEN 290 FT /note="G->D,S: Lack of K(+) uptake activity." FT /evidence="ECO:0000269|PubMed:10359077, FT ECO:0000269|PubMed:16210320" FT MUTAGEN 314 FT /note="G->A: Does not affect Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 316 FT /note="G->A,S: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 317 FT /note="S->C: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 318 FT /note="T->C: Does not affect Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 320 FT /note="T->C: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 321 FT /note="G->A,S: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 322 FT /note="G->C: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 323 FT /note="G->S: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 324 FT /note="I->C: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 325 FT /note="K->C,D,H,Q,R: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 326..328 FT /note="Missing: Abolishes binding to KtrA. Transports Na(+) FT faster." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 326 FT /note="V->C,S,T: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 327 FT /note="S->C: Increases Vmax for K(+) transport." FT /evidence="ECO:0000269|PubMed:20097755" FT MUTAGEN 402 FT /note="G->A,D,S: Exhibits very low K(+) uptake activity." FT /evidence="ECO:0000269|PubMed:16210320" SQ SEQUENCE 455 AA; 49664 MW; 3E93A4F5FC73B2C2 CRC64; MTQFHQRGVF YVPDGKRDKA KGGEPRIILL SFLGVLLPSA VLLTLPVFSV SGLSITDALF TATSAISVTG LGVVDTGQHF TLAGKILLMC LMQIGGLGQM TLSAVLLYMF GVRLSLRQQA LAKEALGQER QVNLRRLVKK IVTFALVAEA IGFVFLSYRW VPEMGWQTGM FYALFHSISA FNNAGFALFS DSMMSFVNDP LVSFTLAGLF IFGGLGFTVI GDVWRHWRKG FHFLHIHTKI MLIATPLLLL VGTVLFWLLE RHNPNTMGSL TTGGQWLAAF FQSASARTAG FNSVDLTQFT QPALLIMIVL MLIGAGSTST GGGIKVSTFA VAFMATWTFL RQKKHVVMFK RTVNWPTVTK SLAIIVVSGA ILTTAMFLLM LTEKASFDKV MFETISAFAT VGLTAGLTAE LSEPGKYIMI VVMIIGRIGP LTLAYMLARP EPTLIKYPED TVLTG //