Q02821 (IMA1_YEAST) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Importin subunit alpha

Alternative name(s):
Karyopherin subunit alpha
Karyopherin-60
Serine-rich RNA polymerase I suppressor protein

Gene names

Name:	SRP1
Synonyms:	KAP60
Ordered Locus Names:	YNL189W
ORF Names:	N1606

Organism

Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast) [Reference proteome]

Taxonomic identifier

559292 [NCBI]

Taxonomic lineage

cellular organisms › Eukaryota › Opisthokonta › Fungi › Dikarya › Ascomycota › saccharomyceta › Saccharomycotina › Saccharomycetes › Saccharomycetales › Saccharomycetaceae › Saccharomyces › Saccharomyces cerevisiae

Protein attributes

Sequence length	542 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Binds specifically and directly to substrates containing either a simple or bipartite NLS motif. Promotes docking of import substrates to the nuclear envelope. Seems to act as a cytosolic receptor for both simple and bipartite NLS motifs By similarity. Ref.2 Ref.8 Ref.12
Subunit structure	Forms a complex with an importin beta subunit. In the nucleus, interacts with NUP2 which accelerate release of NLSs, NUP2 is subsequently displaced by CSE1:RanGTP which mediates re-export and recycling. Interacts with HEH2, SHE2, and STS1. Ref.8 Ref.10 Ref.11 Ref.12
Subcellular location	Cytoplasm › perinuclear region. Note: Mainly localized at the periphery of the nucleus.
Domain	The NLS binding sites are mainly involved in recognition of simple or bipartite NLS motifs. Structurally located within in a helical surface groove they contain several conserved Trp and Asn residues of the corresponding third helices (H3) of ARM repeats which mainly contribute to binding.
Miscellaneous	Binds to nucleoporin FxFG but not GLFG repeat regions. Ran-GTP can disrupt the karyopherin heterodimer by binding to the beta subunit and releases both subunits from the docking site. Present with 2790 molecules/cell in log phase SD medium.
Sequence similarities	Belongs to the importin alpha family. Contains 10 ARM repeats. Contains 1 IBB domain.

Ontologies

Keywords
Biological process	Protein transport Transport
Cellular component	Cytoplasm
Domain	Repeat
Technical term	3D-structure Complete proteome Reference proteome
Gene Ontology (GO)
Biological_process	protein import into nucleus Inferred from mutant phenotype PubMed 19141610. Source: SGD protein targeting to membrane Inferred from mutant phenotype Ref.10. Source: SGD
Cellular_component	cytoplasm Inferred from direct assay PubMed 10725229. Source: SGD integral to membrane Inferred from sequence model PubMed 12192589. Source: SGD nucleus Inferred from direct assay PubMed 10725229PubMed 11914276. Source: SGD perinuclear region of cytoplasm Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular_function	protein transporter activity Inferred from direct assay Ref.6. Source: SGD
Complete GO annotation...

Binary interactions

With	Entry	#Exp.	IntAct	Notes
CSE1	P33307	2	EBI-1797,EBI-5168
KAP95	Q06142	7	EBI-1797,EBI-9145
NUP2	P32499	6	EBI-1797,EBI-12401

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Chain

1 – 542

542

Importin subunit alpha

PRO_0000120744

Regions

Domain

1 – 65

65

IBB

Repeat

89 – 122

34

ARM 1; truncated

Repeat

123 – 162

40

ARM 2

Repeat

163 – 204

42

ARM 3

Repeat

205 – 251

47

ARM 4

Repeat

252 – 288

37

ARM 5

Repeat

289 – 330

42

ARM 6

Repeat

331 – 372

42

ARM 7

Repeat

373 – 417

45

ARM 8

Repeat

418 – 471

54

ARM 9

Repeat

472 – 508

37

ARM 10; atypical

Region

209 – 335

127

NLS binding site 1

Region

419 – 505

87

NLS binding site 2

Experimental info

Mutagenesis

116

1

S → F in SRP1-31; temperature-sensitive mutant; reduced growth rate and chromosome loss.

Mutagenesis

145

1

E → K in SRP1-49; temperature-sensitive mutant; alteration in nucleolar and microtubule morphology.

Mutagenesis

219

1

P → Q in SRP1-1; temperature-sensitive mutant.

Mutagenesis

286

1

D → N in SRP1-3; temperature-sensitive mutant.

Mutagenesis

360

1

E → K in SRP1-2; temperature-sensitive mutant.

Mutagenesis

459

1

G → V in SRP1-54; temperature-sensitive mutant; reduced growth rate.

Secondary structure

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542

Helix Strand Turn

Details...

Helix

15 – 17

3

Helix

89 – 96

8

Beta strand

97 – 99

3

Helix

101 – 114

14

Beta strand

118 – 120

3

Helix

123 – 128

6

Helix

132 – 137

6

Helix

145 – 158

14

Helix

163 – 171

9

Helix

175 – 184

10

Helix

187 – 201

15

Helix

205 – 213

9

Helix

217 – 222

6

Helix

223 – 225

3

Helix

229 – 243

15

Beta strand

246 – 248

3

Helix

252 – 255

4

Helix

256 – 258

3

Helix

259 – 265

7

Helix

271 – 285

15

Helix

289 – 297

9

Helix

301 – 306

6

Helix

307 – 309

3

Helix

313 – 326

14

Helix

331 – 339

9

Helix

342 – 349

8

Helix

355 – 368

14

Helix

373 – 381

9

Helix

385 – 394

10

Helix

397 – 413

17

Turn

414 – 416

3

Helix

419 – 426

8

Helix

430 – 436

7

Turn

437 – 439

3

Helix

442 – 466

25

Helix

472 – 479

8

Helix

482 – 487

6

Helix

488 – 491

4

Beta strand

492 – 494

3

Helix

495 – 508

14

Beta strand

509 – 511

3

Sequences

	Sequence		Length	Mass (Da)
	Q02821 [UniParc]. Last modified July 1, 1993. Version 1. Checksum: 8D3A0CB76F2E7C00	FASTA	542	60,441
	10 20 30 40 50 60 MDNGTDSSTS KFVPEYRRTN FKNKGRFSAD ELRRRRDTQQ VELRKAKRDE ALAKRRNFIP 70 80 90 100 110 120 PTDGADSDEE DESSVSADQQ FYSQLQQELP QMTQQLNSDD MQEQLSATVK FRQILSREHR 130 140 150 160 170 180 PPIDVVIQAG VVPRLVEFMR ENQPEMLQLE AAWALTNIAS GTSAQTKVVV DADAVPLFIQ 190 200 210 220 230 240 LLYTGSVEVK EQAIWALGNV AGDSTDYRDY VLQCNAMEPI LGLFNSNKPS LIRTATWTLS 250 260 270 280 290 300 NLCRGKKPQP DWSVVSQALP TLAKLIYSMD TETLVDACWA ISYLSDGPQE AIQAVIDVRI 310 320 330 340 350 360 PKRLVELLSH ESTLVQTPAL RAVGNIVTGN DLQTQVVINA GVLPALRLLL SSPKENIKKE 370 380 390 400 410 420 ACWTISNITA GNTEQIQAVI DANLIPPLVK LLEVAEYKTK KEACWAISNA SSGGLQRPDI 430 440 450 460 470 480 IRYLVSQGCI KPLCDLLEIA DNRIIEVTLD ALENILKMGE ADKEARGLNI NENADFIEKA 490 500 510 520 530 540 GGMEKIFNCQ QNENDKIYEK AYKIIETYFG EEEDAVDETM APQNAGNTFG FGSNVNQQFN FN

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Cloning and characterization of SRP1, a suppressor of temperature-sensitive RNA polymerase I mutations, in Saccharomyces cerevisiae." Yano R., Oakes M., Yamaghishi M., Dodd J.A., Nomura M. Mol. Cell. Biol. 12:5640-5651(1992) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
[2]	"Yeast Srp1, a nuclear protein related to Drosophila and mouse pendulin, is required for normal migration, division, and integrity of nuclei during mitosis." Kuessel P., Frasch M. Mol. Gen. Genet. 248:351-363(1995) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION. Strain: ATCC 200060 / W303.
[3]	"The nucleotide sequence of Saccharomyces cerevisiae chromosome XIV and its evolutionary implications." Philippsen P., Kleine K., Poehlmann R., Duesterhoeft A., Hamberg K., Hegemann J.H., Obermaier B., Urrestarazu L.A., Aert R., Albermann K., Altmann R., Andre B., Baladron V., Ballesta J.P.G., Becam A.-M., Beinhauer J.D., Boskovic J., Buitrago M.J. , Bussereau F., Coster F., Crouzet M., D'Angelo M., Dal Pero F., De Antoni A., del Rey F., Doignon F., Domdey H., Dubois E., Fiedler T.A., Fleig U., Floeth M., Fritz C., Gaillardin C., Garcia-Cantalejo J.M., Glansdorff N., Goffeau A., Gueldener U., Herbert C.J., Heumann K., Heuss-Neitzel D., Hilbert H., Hinni K., Iraqui Houssaini I., Jacquet M., Jimenez A., Jonniaux J.-L., Karpfinger-Hartl L., Lanfranchi G., Lepingle A., Levesque H., Lyck R., Maftahi M., Mallet L., Maurer C.T.C., Messenguy F., Mewes H.-W., Moestl D., Nasr F., Nicaud J.-M., Niedenthal R.K., Pandolfo D., Pierard A., Piravandi E., Planta R.J., Pohl T.M., Purnelle B., Rebischung C., Remacha M.A., Revuelta J.L., Rinke M., Saiz J.E., Sartorello F., Scherens B., Sen-Gupta M., Soler-Mira A., Urbanus J.H.M., Valle G., Van Dyck L., Verhasselt P., Vierendeels F., Vissers S., Voet M., Volckaert G., Wach A., Wambutt R., Wedler H., Zollner A., Hani J. Nature 387:93-98(1997) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: ATCC 204508 / S288c.
[4]	Saccharomyces Genome Database Submitted (DEC-2009) to the EMBL/GenBank/DDBJ databases Cited for: GENOME REANNOTATION. Strain: ATCC 204508 / S288c.
[5]	"Yeast Srp1p has homology to armadillo/plakoglobin/beta-catenin and participates in apparently multiple nuclear functions including the maintenance of the nucleolar structure." Yano R., Oakes M.L., Tabb M.M., Nomura M. Proc. Natl. Acad. Sci. U.S.A. 91:6880-6884(1994) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS.
[6]	"Identification of a yeast karyopherin heterodimer that targets import substrate to mammalian nuclear pore complexes." Enenkel C., Blobel G., Rexach M. J. Biol. Chem. 270:16499-16502(1995) [PubMed] [Europe PMC] [Abstract] Cited for: IDENTIFICATION.
[7]	"Protein import into nuclei: association and dissociation reactions involving transport substrate, transport factors, and nucleoporins." Rexach M., Blobel G. Cell 83:683-692(1995) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOPORIN REPEAT BINDING REQUIREMENT.
[8]	"Evidence for separable functions of Srp1p, the yeast homolog of importin alpha (Karyopherin alpha): role for Srp1p and Sts1p in protein degradation." Tabb M.M., Tongaonkar P., Vu L., Nomura M. Mol. Cell. Biol. 20:6062-6073(2000) [PubMed] [Europe PMC] [Abstract] Cited for: FUNCTION, INTERACTION WITH STS1.
[9]	"Global analysis of protein expression in yeast." Ghaemmaghami S., Huh W.-K., Bower K., Howson R.W., Belle A., Dephoure N., O'Shea E.K., Weissman J.S. Nature 425:737-741(2003) [PubMed] [Europe PMC] [Abstract] Cited for: LEVEL OF PROTEIN EXPRESSION [LARGE SCALE ANALYSIS].
[10]	"Karyopherin-mediated import of integral inner nuclear membrane proteins." King M.C., Lusk C.P., Blobel G. Nature 442:1003-1007(2006) [PubMed] [Europe PMC] [Abstract] Cited for: INTERACTION WITH HEH2.
[11]	"Nuclear shuttling of She2p couples ASH1 mRNA localization to its translational repression by recruiting Loc1p and Puf6p." Shen Z., Paquin N., Forget A., Chartrand P. Mol. Biol. Cell 20:2265-2275(2009) [PubMed] [Europe PMC] [Abstract] Cited for: INTERACTION WITH SHE2.
[12]	"Sts1 plays a key role in targeting proteasomes to the nucleus." Chen L., Romero L., Chuang S.M., Tournier V., Joshi K.K., Lee J.A., Kovvali G., Madura K. J. Biol. Chem. 286:3104-3118(2011) [PubMed] [Europe PMC] [Abstract] Cited for: FUNCTION, INTERACTION WITH STS1.
[13]	"Crystallographic analysis of the recognition of a nuclear localization signal by the nuclear import factor karyopherin alpha." Conti E., Uy M., Leighton L., Blobel G., Kuriyan J. Cell 94:193-204(1998) [PubMed] [Europe PMC] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.2 ANGSTROMS) OF 89-510.
[14]	"Crystallographic analysis of the specific yet versatile recognition of distinct nuclear localization signals by karyopherin alpha." Conti E., Kuriyan J. Structure 8:329-338(2000) [PubMed] [Europe PMC] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.1 ANGSTROMS) OF 87-509 IN COMPLEX WITH NLS PEPTIDE.
[15]	"Structural basis for Nup2p function in cargo release and karyopherin recycling in nuclear import." Matsuura Y., Lange A., Harreman M.T., Corbett A.H., Stewart M. EMBO J. 22:5358-5369(2003) [PubMed] [Europe PMC] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.6 ANGSTROMS) OF 88-530 IN COMPLEX WITH NUP2.
[16]	"Structural basis for the assembly of a nuclear export complex." Matsuura Y., Stewart M. Nature 432:872-877(2004) [PubMed] [Europe PMC] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.0 ANGSTROMS) OF 1-530 IN COMPLEX WITH CSE1 AND RANGTP.
+	Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ

M75849 Genomic DNA. Translation: AAA35090.1.
Z71465 Genomic DNA. Translation: CAA96083.1.
BK006947 Genomic DNA. Translation: DAA10364.1.

PIR

S30884.

RefSeq

NP_014210.1. NM_001183027.1.

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1BK5	X-ray	2.20	A/B	89-510	[»]
1BK6	X-ray	2.80	A/B	89-510	[»]
1EE4	X-ray	2.10	A/B	87-509	[»]
1EE5	X-ray	2.40	A	87-510	[»]
1UN0	X-ray	2.60	A/B	88-530	[»]
1WA5	X-ray	2.00	B	1-530	[»]
2C1T	X-ray	2.60	A/B	88-541	[»]

ProteinModelPortal

Q02821.

SMR

Q02821. Positions 37-513.

ModBase

Search...

Protein-protein interaction databases

DIP

DIP-728N.

IntAct

Q02821. 167 interactions.

MINT

MINT-386354.

STRING

4932.YNL189W.

Proteomic databases

PaxDb

Q02821.

PeptideAtlas

Q02821.

Protocols and materials databases

StructuralBiologyKnowledgebase

Search...

Genome annotation databases

EnsemblFungi

YNL189W; YNL189W; YNL189W.

GeneID

855532.

KEGG

sce:YNL189W.

Organism-specific databases

CYGD

YNL189w.

SGD

S000005133. SRP1.

Phylogenomic databases

eggNOG

COG5064.

GeneTree

ENSGT00610000085856.

HOGENOM

HOG000167616.

OMA

QPDWTTI.

OrthoDB

EOG408RH7.

Gene expression databases

Genevestigator

Q02821.

GermOnline

YNL189W. Saccharomyces cerevisiae.

Family and domain databases

Gene3D

1.25.10.10. 1 hit.

InterPro

IPR011989. ARM-like.
IPR016024. ARM-type_fold.
IPR000225. Armadillo.
IPR002652. Importin-a_IBB.
IPR024931. Importing_su_alpha.
[Graphical view]

Pfam

PF00514. Arm. 8 hits.
PF01749. IBB. 1 hit.
[Graphical view]

PIRSF

PIRSF005673. Importin_alpha. 1 hit.

SMART

SM00185. ARM. 8 hits.
[Graphical view]

SUPFAM

SSF48371. ARM-type_fold. 1 hit.

PROSITE

PS50176. ARM_REPEAT. 2 hits.
PS51214. IBB. 1 hit.
[Graphical view]

ProtoNet

Search...

Other

EvolutionaryTrace

Q02821.

NextBio

979583.

Entry information

Entry name

IMA1_YEAST

Accession

Primary (citable) accession number: Q02821
Secondary accession number(s): D6W0Z8

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 1, 1993
Last sequence update:	July 1, 1993
Last modified:	April 3, 2013
This is version 130 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Fungal Protein Annotation Program