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Karyopherin alpha 3 (importin alpha 4)
Symbols KPNA3 ; IPOA4; SRP1; SRP1gamma; SRP4; hSRP1
External IDs OMIM601892 MGI1100863 HomoloGene20520 GeneCards: KPNA3 Gene
RNA expression pattern
PBB GE KPNA3 221502 at tn.png
PBB GE KPNA3 221503 s at tn.png
More reference expression data
Species Human Mouse
Entrez 3839 16648
Ensembl ENSG00000102753 ENSMUSG00000021929
UniProt O00505 O35344
RefSeq (mRNA) NM_002267 NM_008466
RefSeq (protein) NP_002258 NP_032492
Location (UCSC) Chr 13:
50.27 – 50.37 Mb
Chr 14:
61.37 – 61.44 Mb
PubMed search [1] [2]

Importin subunit alpha-3 is a protein that in humans is encoded by the KPNA3 gene.[1][2]

The transport of molecules between the nucleus and the cytoplasm in eukaryotic cells is mediated by the nuclear pore complex (NPC) which consists of 60–100 proteins and is probably 120 million daltons in molecular size. Small molecules (up to 70 kD) can pass through the nuclear pore by nonselective diffusion; larger molecules are transported by an active process. Most nuclear proteins contain short basic amino acid sequences known as nuclear localization signals (NLSs). KPNA3, encodes a protein similar to certain nuclear transport proteins of Xenopus and human. The predicted amino acid sequence shows similarity to Xenopus importin, yeast SRP1, and human RCH1 (KPNA2), respectively. The similarities among these proteins suggests that karyopherin alpha-3 may be involved in the nuclear transport system.[3]


KPNA3 has been shown to interact with KPNB1.[2][4]


  1. ^ Takeda S, Fujiwara T, Shimizu F, Kawai A, Shinomiya K, Okuno S, Ozaki K, Katagiri T, Shimada Y, Nagata M, Watanabe T, Takaichi A, Kuga Y, Suzuki M, Hishigaki H, Takahashi E, Shin S, Nakamura Y, Hirai Y (Jun 1997). "Isolation and mapping of karyopherin alpha 3 (KPNA3), a human gene that is highly homologous to genes encoding Xenopus importin, yeast SRP1 and human RCH1". Cytogenet Cell Genet 76 (1–2): 87–93. doi:10.1159/000134521. PMID 9154134. 
  2. ^ a b Nachury MV, Ryder UW, Lamond AI, Weis K (Feb 1998). "Cloning and characterization of hSRP1 gamma, a tissue-specific nuclear transport factor". Proc Natl Acad Sci U S A 95 (2): 582–7. doi:10.1073/pnas.95.2.582. PMC 18463. PMID 9435235. 
  3. ^ "Entrez Gene: KPNA3 karyopherin alpha 3 (importin alpha 4)". 
  4. ^ Köhler, M; Speck C; Christiansen M; Bischoff F R; Prehn S; Haller H; Görlich D; Hartmann E (Nov 1999). "Evidence for distinct substrate specificities of importin alpha family members in nuclear protein import". Mol. Cell. Biol. (UNITED STATES) 19 (11): 7782–91. ISSN 0270-7306. PMC 84838. PMID 10523667. 

Further reading[edit]