PMID- 11124253 OWN - NLM STAT- MEDLINE DCOM- 20010503 LR - 20210209 IS - 0021-9258 (Print) IS - 0021-9258 (Linking) VI - 276 IP - 12 DP - 2001 Mar 23 TI - Molecular cloning of a novel importin alpha homologue from rice, by which constitutive photomorphogenic 1 (COP1) nuclear localization signal (NLS)-protein is preferentially nuclear imported. PG - 9322-9 AB - Nuclear import of proteins that contain classical nuclear localization signals (NLS) is initiated by importin alpha, a protein that recognizes and binds to the NLS in the cytoplasm. In this paper, we have cloned a cDNA for a novel importin alpha homologue from rice which is in addition to our previously isolated rice importin alpha1a and alpha2, and we have named it rice importin alpha1b. In vitro binding and nuclear import assays using recombinant importin alpha1b protein demonstrate that rice importin alpha1b functions as a component of the NLS-receptor in plant cells. Analysis of the transcript levels for all three rice importin alpha genes revealed that the genes were not only differentially expressed but that they also responded to dark-adaptation in green leaves. Furthermore, we also show that the COP1 protein bears a bipartite-type NLS and its nuclear import is mediated preferentially by the rice importin alpha1b. These data suggest that each of the different rice importin alpha proteins carry distinct groups of nuclear proteins, such that multiple isoforms of importin alpha contribute to the regulation of plant nuclear protein transport. FAU - Jiang, C J AU - Jiang CJ AD - National Institute of Agrobiological Resources, Tsukuba, Ibaraki 305-8602, Japan. cjjiang@abr.affrc.go.jp FAU - Shoji, K AU - Shoji K FAU - Matsuki, R AU - Matsuki R FAU - Baba, A AU - Baba A FAU - Inagaki, N AU - Inagaki N FAU - Ban, H AU - Ban H FAU - Iwasaki, T AU - Iwasaki T FAU - Imamoto, N AU - Imamoto N FAU - Yoneda, Y AU - Yoneda Y FAU - Deng, X W AU - Deng XW FAU - Yamamoto, N AU - Yamamoto N LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20001220 PL - United States TA - J Biol Chem JT - The Journal of biological chemistry JID - 2985121R RN - 0 (Arabidopsis Proteins) RN - 0 (Carrier Proteins) RN - 0 (DNA, Complementary) RN - 0 (Karyopherins) RN - 0 (Nuclear Localization Signals) RN - 0 (Nuclear Proteins) RN - 0 (Plant Proteins) RN - 0 (RNA, Messenger) RN - EC 2.3.2.27 (AT2G32950 protein, Arabidopsis) RN - EC 2.3.2.27 (Ubiquitin-Protein Ligases) RN - KOO5CM684H (Digitonin) SB - IM MH - Amino Acid Sequence MH - *Arabidopsis Proteins MH - Base Sequence MH - Carrier Proteins/chemistry/*metabolism MH - Cell Nucleus/metabolism MH - Cloning, Molecular MH - DNA, Complementary MH - Digitonin/pharmacology MH - HeLa Cells MH - Humans MH - Karyopherins MH - Molecular Sequence Data MH - *Nuclear Localization Signals MH - Nuclear Proteins/*genetics/metabolism MH - Oryza/*genetics MH - Plant Proteins/chemistry/*metabolism MH - Protein Binding MH - Protein Transport MH - RNA, Messenger/genetics MH - Sequence Homology, Amino Acid MH - *Ubiquitin-Protein Ligases EDAT- 2001/01/01 19:15 MHDA- 2001/05/05 10:01 CRDT- 2001/01/01 19:15 PHST- 2001/01/01 19:15 [pubmed] PHST- 2001/05/05 10:01 [medline] PHST- 2001/01/01 19:15 [entrez] AID - S0021-9258(19)46237-6 [pii] AID - 10.1074/jbc.M006430200 [doi] PST - ppublish SO - J Biol Chem. 2001 Mar 23;276(12):9322-9. doi: 10.1074/jbc.M006430200. Epub 2000 Dec 20.