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 15-MAR-2017, entry version 36. 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; OC Vibrionaceae; Vibrio. OX NCBI_TaxID=663; RN [1] RP NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION, AND GENE NAME. RX PubMed=9642210; 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, ENZYME 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 RT KtrB causes a two orders of magnitude decrease in the affinities for RT both K+ and Na+ of the Na+ dependent K+ uptake system KtrAB from RT Vibrio alginolyticus."; RL FEBS Lett. 450:217-220(1999). RN [3] RP FUNCTION, BIOPHYSICOCHEMICAL PROPERTIES, SUBUNIT, SUBCELLULAR RP LOCATION, DOMAIN, AND MUTAGENESIS OF GLY-70; GLY-185; GLY-290 AND RP GLY-402. RX PubMed=16210320; DOI=10.1074/jbc.M507647200; RA Tholema N., Vor der Brueggen M., Maeser P., Nakamura T., RA Schroeder J.I., 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 RT system 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., RA Bakker E.P.; RT "ATP binding to the KTN/RCK subunit KtrA from the K+ -uptake system RT KtrAB of Vibrio alginolyticus: its role in the formation of the KtrAB RT complex and 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; RP LYS-325; 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 RT gate controlling K+ transport by the KtrAB system from Vibrio RT alginolyticus."; RL J. Biol. Chem. 285:10318-10327(2010). CC -!- FUNCTION: Part of the Na(+)-dependent high affinity K(+) uptake CC system KtrAB. KtrB is the K(+)-translocating subunit. CC {ECO:0000269|PubMed:10359077, ECO:0000269|PubMed:16210320, CC ECO:0000269|PubMed:9642210}. CC -!- ENZYME 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 CC {ECO:0000269|PubMed:10359077, ECO:0000269|PubMed:16210320, CC ECO:0000269|PubMed:20097755}; Multi-pass membrane protein CC {ECO:0000269|PubMed:10359077, ECO:0000269|PubMed:16210320, CC ECO:0000269|PubMed:20097755}. CC -!- DOMAIN: Contain four repeated domains, each composed of two CC transmembrane helices connected by a putative pore loop (p-loop). CC Four conserved glycine residues in the p-loops are part of a CC selectivity filter for K(+) ions. {ECO:0000269|PubMed:10359077, CC ECO:0000269|PubMed:16210320}. CC -!- MISCELLANEOUS: KtrB alone mediates slow Na(+)-independent K(+) CC uptake, as well as K(+)-independent Na(+) uptake. CC {ECO:0000305|PubMed:20097755}. CC -!- SIMILARITY: Belongs to the TrkH potassium transport family. Ktr CC (TC 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 SMR; O87953; -. DR TCDB; 2.A.38.4.2; the k(+) transporter (trk) family. 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:0022820; F:potassium ion 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; KW Potassium; Potassium transport; Transmembrane; Transmembrane helix; KW Transport. FT CHAIN 1 455 Ktr system potassium uptake protein B. FT /FTId=PRO_0000430033. FT TRANSMEM 27 47 Helical. {ECO:0000255}. FT INTRAMEM 54 74 {ECO:0000255}. FT TRANSMEM 86 106 Helical. {ECO:0000255}. FT TRANSMEM 141 161 Helical. {ECO:0000255}. FT INTRAMEM 169 189 {ECO:0000255}. FT TRANSMEM 201 221 Helical. {ECO:0000255}. FT TRANSMEM 240 260 Helical. {ECO:0000255}. FT INTRAMEM 291 313 {ECO:0000255}. FT TRANSMEM 318 340 Helical. {ECO:0000255}. FT TRANSMEM 362 382 Helical. {ECO:0000255}. FT INTRAMEM 390 410 {ECO:0000255}. FT TRANSMEM 418 438 Helical. {ECO:0000255}. FT MUTAGEN 70 70 G->A,S: Decrease in K(+) uptake activity. FT {ECO:0000269|PubMed:16210320}. FT MUTAGEN 70 70 G->D: Exhibits very low K(+) uptake FT activity. {ECO:0000269|PubMed:16210320}. FT MUTAGEN 185 185 G->A,D: Decrease in K(+) uptake activity. FT {ECO:0000269|PubMed:16210320}. FT MUTAGEN 185 185 G->S: Exhibits very low K(+) uptake FT activity. {ECO:0000269|PubMed:16210320}. FT MUTAGEN 290 290 G->A: Decrease in K(+) uptake activity. FT {ECO:0000269|PubMed:10359077, FT ECO:0000269|PubMed:16210320}. FT MUTAGEN 290 290 G->D,S: Lack of K(+) uptake activity. FT {ECO:0000269|PubMed:10359077, FT ECO:0000269|PubMed:16210320}. FT MUTAGEN 314 314 G->A: Does not affect Vmax for K(+) FT transport. {ECO:0000269|PubMed:20097755}. FT MUTAGEN 316 316 G->A,S: Increases Vmax for K(+) FT transport. {ECO:0000269|PubMed:20097755}. FT MUTAGEN 317 317 S->C: Increases Vmax for K(+) transport. FT {ECO:0000269|PubMed:20097755}. FT MUTAGEN 318 318 T->C: Does not affect Vmax for K(+) FT transport. {ECO:0000269|PubMed:20097755}. FT MUTAGEN 320 320 T->C: Increases Vmax for K(+) transport. FT {ECO:0000269|PubMed:20097755}. FT MUTAGEN 321 321 G->A,S: Increases Vmax for K(+) FT transport. {ECO:0000269|PubMed:20097755}. FT MUTAGEN 322 322 G->C: Increases Vmax for K(+) transport. FT {ECO:0000269|PubMed:20097755}. FT MUTAGEN 323 323 G->S: Increases Vmax for K(+) transport. FT {ECO:0000269|PubMed:20097755}. FT MUTAGEN 324 324 I->C: Increases Vmax for K(+) transport. FT {ECO:0000269|PubMed:20097755}. FT MUTAGEN 325 325 K->C,D,H,Q,R: Increases Vmax for K(+) FT transport. {ECO:0000269|PubMed:20097755}. FT MUTAGEN 326 328 Missing: Abolishes binding to KtrA. FT Transports Na(+) faster. FT {ECO:0000269|PubMed:20097755}. FT MUTAGEN 326 326 V->C,S,T: Increases Vmax for K(+) FT transport. {ECO:0000269|PubMed:20097755}. FT MUTAGEN 327 327 S->C: Increases Vmax for K(+) transport. FT {ECO:0000269|PubMed:20097755}. FT MUTAGEN 402 402 G->A,D,S: Exhibits very low K(+) uptake FT activity. {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 //