Reviewed, UniProtKB/Swiss-Prot Q93XI5 (HKT2_ORYSI)

Names and origin

Protein names

Recommended name:
    Cation transporter HKT2
      Short name=OsHKT2
Alternative name(s):
    Po-OsHKT2

Gene names

Name:

HKT2

Organism

Oryza sativa subsp. indica (Rice)

Taxonomic identifier

39946 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › Liliopsida › Poales › Poaceae › BEP clade › Ehrhartoideae › Oryzeae › Oryza

Protein attributes

Sequence length	530 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Seems to be involved in regulation of K(+)/Na(+) homeostasis. Seems to act as a potassium-sodium cotransporter, which mediates increased potassium uptake under external sodium accumulation and contributes to salt-tolerance in cultivar indica Pokkali.
Subcellular location	Membrane; Multi-pass membrane proteinProbable.
Induction	By potassium starvation in roots. Down-regulated by sodium.
Domain	HKT transporters are proposed to contain 4 pore-forming regions enclosed by transmembrane segments with each containing a potassium channel-like selectivity filter motif.
Sequence similarities	Belongs to the trkH potassium transport family. HKT subfamily.
Caution	HKT2 is found in salt-tolerant cultivar indica Pokkali. It does not exist in cultivar indica 93-11 or japonica Nipponbare.

Ontologies

Keywords
Biological process	Ion transport Potassium transport Sodium transport Transport
Cellular component	Membrane
Domain	Transmembrane
Ligand	Potassium Sodium
Gene Ontology (GO)
Biological process	sodium ion transport Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	potassium ion binding Inferred from electronic annotation. Source: UniProtKB-KW sodium ion binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 530	530	Cation transporter HKT2		PRO_0000070467
Regions
	Topological domain	1 – 40	40	Cytoplasmic Potential
	Transmembrane	41 – 61	21	1 Potential
	Transmembrane	102 – 122	21	2 Potential
	Topological domain	123 – 186	64	Cytoplasmic Potential
	Transmembrane	187 – 207	21	3 Potential
	Transmembrane	260 – 280	21	4 Potential
	Topological domain	281 – 317	37	Cytoplasmic Potential
	Transmembrane	318 – 338	21	5 Potential
	Transmembrane	372 – 392	21	6 Potential
	Topological domain	393 – 420	28	Cytoplasmic Potential
	Transmembrane	421 – 441	21	7 Potential
	Transmembrane	494 – 514	21	8 Potential
	Topological domain	515 – 530	16	Cytoplasmic Potential
Experimental info
	Mutagenesis	88	1	G → S: Loss of selectivity for potassium uptake

Sequences

	Sequence		Length	Mass (Da)
	Q93XI5-1 [UniParc]. Last modified December 1, 2001. Version 1. Checksum: 73087CF493AD3360	FASTA	530	59,152
	10 20 30 40 50 60 MTSIYQEFIH TKCQSFRSIG RYVLHSIVLI YRFVSLHVHP FWIQLSYFLL ISILGSVLLM 70 80 90 100 110 120 FLKPSSPEFK PGYIDMLFLS TSAMTVSGLS TIEMEVLSSS QIVVLTLLML VGGEVFVSFL 130 140 150 160 170 180 GLMLRLKHKH NPEFSGDRVS SVPIELDTIE PTRTVMSSEE LQIEAAAPDV PSSTIKDLKR 190 200 210 220 230 240 SKRLRWFLGF VVFSYFVVIH VVGFLLVLWY ISRVSSAKAP LKKKGINIAL FSFSVTVSSF 250 260 270 280 290 300 ANGGLVPTNE NMAIFSKNPG LLLLFIGQIL AGNTLYPLFL RILIWFLGKV TKLKDLKLMI 310 320 330 340 350 360 KNSDELQYDY LLPKLPTAFL ASTVIGLMAS LVTLFGSVDW NSSVFDGLSS YQKIINALFM 370 380 390 400 410 420 AVNARHSGEN SIDCSLIAPA VLVLFIILMY LPPSTTFALS NGDEKTANKK AKRKLGLVVR 430 440 450 460 470 480 NLAFSQLACN AVFVIVALIT ERSRLRNDPL NFSALNMIFE VISAYGNVGL TTGYSCSRLQ 490 500 510 520 530 KLHPGSICQD KPYSLSGWWS DEGKLLLVSV MLYGRLKAFT KGTGEYWRLW

References

[1]

"Two types of HKT transporters with different properties of Na+ and K+ transport in Oryza sativa." Horie T., Yoshida K., Nakayama H., Yamada K., Oiki S., Shinmyo A. Plant J. 27:129-138(2001) [PubMed: 11489190] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, INDUCTION. Strain: cv. Pokkali. Tissue: Seedling root.

[2]

"Glycine residues in potassium channel-like selectivity filters determine potassium selectivity in four-loop-per-subunit HKT transporters from plants." Maeser P., Hosoo Y., Goshima S., Horie T., Eckelman B., Yamada K., Yoshida K., Bakker E.P., Shinmyo A., Oiki S., Schroeder J.I., Uozumi N. Proc. Natl. Acad. Sci. U.S.A. 99:6428-6433(2002) [PubMed: 11959905] [Abstract] Cited for: FUNCTION, DOMAIN, MUTAGENESIS OF GLY-88.

Cross-references

Sequence databases
EMBLGenBankDDBJ	AB061313 mRNA. Translation: BAB61791.1.
3D structure databases
ModBase	Search...
Organism-specific databases
Gramene	Q93XI5.
Family and domain databases
InterPro	IPR003445. Cat_transpt. IPR004773. Ktransp_euk. [Graphical view]
Pfam	PF02386. TrkH. 1 hit. [Graphical view]
TIGRFAMs	TIGR00934. 2a38euk. 1 hit.
BLOCKS	Search...
ProtoNet	Search...

Entry information

Entry name

HKT2_ORYSI

Accession

Primary (citable) accession number: Q93XI5

Entry history

Integrated into UniProtKB/Swiss-Prot:	December 20, 2005
Last sequence update:	December 1, 2001
Last modified:	November 4, 2008
This is version 23 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

PPAP (Plant Proteome Annotation Project)