A novel nuclear localization signal in the human single-minded proteins SIM1 and SIM2

Akiko Yamaki, Jun Kudoh, Nobuyoshi Shimizu, Yoshiko Shimizu

研究成果: Article査読

17 被引用数 (Scopus)


Human Single-minded 1 (SIM1) and SIM2 genes were found as homologs of Drosophila sim gene which plays a key role in the midline cell lineage of the central nervous system. SIM proteins belong to a family of transcription factors, called bHLH/PAS. Here we examined the intracellular localization of SIM proteins using the expression constructs of whole SIM2 or SIM1 protein fused with enhanced green fluorescent protein (EGFP). The transient expression analysis revealed the nuclear localization of SIM proteins in the cultured cells. To identify the nuclear localization signal, we made expression constructs of EGFP-fusion protein consisting of various portions of SIM proteins. Transfection assay showed the presence of NLS activity in the small region of 23 and 21 amino acid residues at the central part of SIM2 and SIM1 proteins, respectively. Further analysis with amino acid substitution of this small region of SIM2 protein revealed the critical role of five amino acid residues (Arg367, Lys373, Pro385, Tyr386, and Gln389) in NLS activity. The consensus sequence of RKxxKx[K/R]xxxxKxKxRxxPY was estimated as a presumptive NLS in SIM proteins from various species. Thus, the NLS consisting of a cluster of basic amino acids with Pro and Tyr at the C-terminal end is novel and well conserved in the SIM proteins during evolution.

ジャーナルBiochemical and Biophysical Research Communications
出版ステータスPublished - 2004 1月 16

ASJC Scopus subject areas

  • 生物理学
  • 生化学
  • 分子生物学
  • 細胞生物学


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