Gem, a member of the Rad,Gem/Kir subfamily of small G-proteins, has unique sequence features. We report here the crystallographic structure determination of the Gem G-domain in complex with nucleotide to 2.4 Å resolution. Although the basic Ras protein fold is maintained, the Gem switch regions emphatically differ from the Ras paradigm. Our ensuing biochemical characterization indicates that Gem G-domain markedly prefers GDP over GTP. Two known functions of Gem are distinctly affected by spatially separated clusters of mutations.
Bibliographical noteFunding Information:
Thanks go to the staff of ID14-4 (ESRF, France) for assistance with diffraction experiments. We thank Doug Andres for generously sharing Cav β expression constructs. Preliminary studies were supported by a grant from the US–Israel Binational Science Foundation (JAH, KK). Continuing work has been funded by a grant to JAH from the Israel Cancer Research Fund and by NIH grant EY 03529 to ZS. Appendix A
- Calcium channel