The Structure of Importin-beta Bound to SREBP-2: Nuclear Import of a Transcription FactorLee, S.J., Sekimoto, T., Yamashita, E., Nagoshi, E., Nakagawa, A., Imamoto, N., Yoshimura, M., Sakai, H., Chong, K.T., Tsukihara, T., Yoneda, Y.
(2003) Science 302: 1571-1575
- PubMed: 14645851
- DOI: https://doi.org/10.1126/science.1088372
- Primary Citation of Related Structures:
- PubMed Abstract:
The sterol regulatory element-binding protein 2 (SREBP-2), a nuclear transcription factor that is essential for cholesterol metabolism, enters the nucleus through a direct interaction of its helix-loop-helix leucine zipper domain with importin-beta. We show the crystal structure of importin-beta complexed with the active form of SREBP-2. Importin-beta uses characteristic long helices like a pair of chopsticks to interact with an SREBP-2 dimer. Importin-beta changes its conformation to reveal a pseudo-twofold symmetry on its surface structure so that it can accommodate a symmetric dimer molecule. Importin-beta may use a similar strategy to recognize other dimeric cargoes.
Institute for Protein Research, Graduate School of Frontier Biosciences, Osaka University, Yamadaoka 2-2, Suita, Osaka 565-0871, Japan.