Article info 2015 3 (3)    003  (03)   pp.  117 ~ 122
Title Structure and nuclear transport mechanism of HSP70 nuclear transporter, Hikeshi
Authors Jinsue Song, Hyerim Hong, Jong Il Ko, Eun-Joo Park, Sang Mi Park, Se-Young Son and Soo Jae Lee*
Institutions College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763, Korea. *Correspondence: sjlee@chungbuk.ac.kr
Abstract Translocation of macromolecules across the nuclear membrane under the normal conditions has been well studied, but the mechanism of nuclear translocation under the heat-shock stress conditions remain elusive. Hikeshi is a nuclear transport receptor required for cell survival after heat-shock stress. It is in charge of heat shock-induced nuclear import of 70-kilodalton heat shock proteins (HSP70s) through interactions with FG repeats in nuclear pore complexes. Hikeshi forms an “asymmetric” homodimer that is a characteristic feature. Asymmetry of Hikeshi arises from the distinct conformation of the C-terminal domain and the flexibility of the linker regions which areas are essential for nuclear import of HSP70. A unique extended-loop (E-loop) in the N-terminal domain controls the interactions of Hikeshi with FG-Nups by opening or closing the F97 binding site. The recently reported X-ray structure of Hikeshi explains how Hikeshi participates in the nuclear import regulation through FG-Nups recognition, and which part of Hikeshi affects its binding to HSP70. In this review, we will discuss the structural insight on the highly unique import receptor Hikeshi in heat-shock stress condition.