Crystal structure of the GTPase-activating domain of human p120GAP and implications for the interaction with Ras.Scheffzek, K., Lautwein, A., Kabsch, W., Ahmadian, M.R., Wittinghofer, A.
(1996) Nature 384: 591-596
- PubMed: 8955277
- DOI: https://doi.org/10.1038/384591a0
- Primary Citation of Related Structures:
- PubMed Abstract:
Ras-related GTP-binding proteins function as molecular switches which cycle between GTP-bound 'on'- and GDP-bound 'off'-states. GTP hydrolysis is the common timing mechanism that mediates the return from the 'on' to the 'off'-state. It is usually slow but can be accelerated by orders of magnitude upon interaction with GTPase-activating proteins (GAPs). In the case of Ras, a major regulator of cellular growth, point mutations are found in approximately 30% of human tumours which render the protein unable to hydrolyse GTP, even in the presence of Ras-GAPs. The first structure determination of a GTPase-activating protein reveals the catalytically active fragment of the Ras-specific p120GAP (ref. 2), GAP-334, as an elongated, exclusively helical protein which appears to represent a novel protein fold. The molecule consists of two domains, one of which contains all the residues conserved among different GAPs for Ras. From the location of conserved residues around a shallow groove in the central domain we can identify the site of interaction with Ras x GTP. This leads to a model for the interaction between Ras and GAP that satisfies numerous biochemical and genetic data on this important regulatory process.
Max-Planck-Institut für molekulare Physiologie, Dortmund, Germany.