Reviewed, UniProtKB/Swiss-Prot Q02821 (IMA1_YEAST)

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 (Baker's yeast) [Complete proteome]

Taxonomic identifier

4932 [NCBI]

Taxonomic lineage

Eukaryota › Fungi › Dikarya › Ascomycota › Saccharomycotina › Saccharomycetes › Saccharomycetales › Saccharomycetaceae › Saccharomyces

Protein attributes

Sequence length	542 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
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.
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.
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
Gene Ontology (GO)
Biological process	protein import into nucleus Inferred from electronic annotation. Source: InterPro protein targeting to membrane Inferred from mutant phenotype. Source: SGD
Cellular component	cytoplasm Inferred from electronic annotation. Source: InterPro nuclear pore Inferred from electronic annotation. Source: InterPro
Molecular function	protein transmembrane transporter activity Traceable author statement. Source: SGD
Complete GO annotation...

Binary interactions

With	Entry	#Exp.	IntAct	Notes
	P25659	1	EBI-1797,EBI-21985
	P36068	1	EBI-1797,EBI-26866
	P38276	1	EBI-1797,EBI-21630
	P40892	1	EBI-1797,EBI-26263
	P43582	1	EBI-1797,EBI-22766
	P47115	1	EBI-1797,EBI-25514
	Q02895	1	EBI-1797,EBI-35030
AAD14	P42884	1	EBI-1797,EBI-1994
ACE1	P15315	1	EBI-1797,EBI-2065
ACS1	Q01574	1	EBI-1797,EBI-2128
APE1	P14904	1	EBI-1797,EBI-2571
ATG19	P35193	1	EBI-1797,EBI-29291
BNA6	P43619	1	EBI-1797,EBI-11793
CAR1	P00812	1	EBI-1797,EBI-2856
CAT2	P32796	1	EBI-1797,EBI-3935
CDD1	Q06549	1	EBI-1797,EBI-4455
ECM31	P38122	1	EBI-1797,EBI-12901
FBP1	P09201	1	EBI-1797,EBI-6744
FOL2	P51601	1	EBI-1797,EBI-7429
GLK1	P17709	1	EBI-1797,EBI-8744
HEM2	P05373	1	EBI-1797,EBI-8239
HMO1	Q03973	1	EBI-1797,EBI-33047
HPA2	Q06592	1	EBI-1797,EBI-34205
HPA3	P39979	1	EBI-1797,EBI-22400
HSP10	P38910	1	EBI-1797,EBI-4553
HSP26	P15992	1	EBI-1797,EBI-8555
HSP31	Q04432	1	EBI-1797,EBI-35591
HUA2	Q12134	1	EBI-1797,EBI-37262
IMD2	P38697	1	EBI-1797,EBI-9186
ISN1	Q99312	1	EBI-1797,EBI-36349
KAP95	Q06142	1	EBI-1797,EBI-9145
LSB1	P53281	1	EBI-1797,EBI-23329
MBB1	P39534	1	EBI-1797,EBI-26211
MCM21	Q06675	1	EBI-1797,EBI-32349
MET3	P08536	1	EBI-1797,EBI-10753
NDK1	P36010	1	EBI-1797,EBI-11968
NIF3	P53081	1	EBI-1797,EBI-12063
NKP1	Q12493	1	EBI-1797,EBI-35840
NMA1	Q06178	1	EBI-1797,EBI-11803
NMA2	P53204	1	EBI-1797,EBI-23073
PDS1	P40316	1	EBI-1797,EBI-16908
PNC1	P53184	1	EBI-1797,EBI-23741
PNP1	Q05788	1	EBI-1797,EBI-13604
RIB3	Q99258	1	EBI-1797,EBI-15164
RNT1	Q02555	1	EBI-1797,EBI-15673
SAE2	P46946	1	EBI-1797,EBI-16440
SMT3	Q12306	1	EBI-1797,EBI-17490
SNZ3	P43545	1	EBI-1797,EBI-17629
SPC19	Q03954	1	EBI-1797,EBI-38809
TDH3	P00359	1	EBI-1797,EBI-7218
THG1	P53215	1	EBI-1797,EBI-23112
THI4	P32318	1	EBI-1797,EBI-19215
THR1	P17423	1	EBI-1797,EBI-9685
TSA2	Q04120	1	EBI-1797,EBI-19631
TVP15	Q03860	1	EBI-1797,EBI-37537
YHL018W	P38744	1	EBI-1797,EBI-13396
YIP3	P53633	1	EBI-1797,EBI-25301

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

90 – 96

7

Helix

101 – 114

14

Helix

123 – 128

6

Helix

132 – 137

6

Helix

145 – 159

15

Helix

163 – 171

9

Helix

175 – 184

10

Helix

187 – 203

17

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 – 284

14

Helix

289 – 297

9

Helix

301 – 307

7

Helix

313 – 326

14

Helix

331 – 339

9

Helix

342 – 349

8

Helix

355 – 369

15

Helix

373 – 381

9

Helix

385 – 394

10

Helix

397 – 412

16

Turn

413 – 416

4

Helix

418 – 426

9

Helix

430 – 439

10

Helix

442 – 465

24

Helix

472 – 480

9

Helix

482 – 488

7

Helix

489 – 491

3

Helix

495 – 508

14

Sequences

	Sequence		Length	Mass (Da)
	Q02821-1 [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: 1448093] [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: 7565597] [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: 9169873] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: ATCC 204508 / S288c.
[4]	"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: 8041713] [Abstract] Cited for: MUTAGENESIS.
[5]	"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: 7622450] [Abstract] Cited for: IDENTIFICATION.
[6]	"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: 8521485] [Abstract] Cited for: NUCLEOPORIN REPEAT BINDING REQUIREMENT.
[7]	"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: 14562106] [Abstract] Cited for: LEVEL OF PROTEIN EXPRESSION [LARGE SCALE ANALYSIS].
[8]	"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: 9695948] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.2 ANGSTROMS) OF 89-510.
[9]	"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: 10745017] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.1 ANGSTROMS) OF 87-509 IN COMPLEX WITH NLS PEPTIDE.
[10]	"Structural basis for Nup2p function in cargo release and karyopherin recycling in nuclear import."