Nuclear localization mechanism of Hsp105beta and its possible function in mammalian cells.
Hsp105alpha and Hsp105beta are mammalian stress proteins of the Hsp105/110 family. We have shown that Hsp105beta localizes to the nucleus, whereas Hsp105alpha localizes to the cytoplasm of mammalian cells. Hsp105alpha localizes in the cytoplasm, as the nuclear export signal (NES) activity rather than nuclear localization signal (NLS) activity dominates in Hsp105alpha, due to suppression of the NLS activity. In this study, we determined the mechanisms behind the nuclear localization of Hsp105beta, and revealed that the NES was suppressed by the N-terminal (amino acids 3-10) or C-terminal (amino acids 699-756) region of Hsp105beta, and the NLS activity rather than NES activity seemed to dominate in Hsp105beta. Furthermore, as Hsp105beta which localizes in the nucleus, functioned as an inducer of Hsp70 in mammalian cells, Hsp105 family proteins may play an important role in the protection of cells against deleterious stressor together with Hsp70.
Saito
Youhei
Y
Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
Yamagishi
Nobuyuki
N
Hatayama
Takumi
T
D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism; D050957:HSP110 Heat-Shock Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D019913:Nuclear Localization Signals / Q000378:metabolism; D014162:Transfection
D050883:HSC70 Heat-Shock Proteins; D050957:HSP110 Heat-Shock Proteins; C490783:Hsp105 protein, mouse; D019913:Nuclear Localization Signals