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Crystal Structure of a Human K‑Ras G12D Mutant in Complex with GDP and the Cyclic Inhibitory Peptide KRpep-2d

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journal contribution
posted on 10.05.2017, 00:00 by Satoshi Sogabe, Yusuke Kamada, Masanori Miwa, Ayumu Niida, Tomoya Sameshima, Masahiro Kamaura, Kazuko Yonemori, Shigekazu Sasaki, Jun-ichi Sakamoto, Kotaro Sakamoto
The Ras proteins play roles in cell differentiation, proliferation, and survival. Aberrant signaling through Ras-mediated pathways in tumor cells occurs as a result of several types of mutational damage, which most frequently affects the amino acids G12, G13, and Q61. Recently, KRpep-2d was identified as a K-Ras­(G12D) selective inhibitory peptide against the G12D mutant of K-Ras, which is a key member of the Ras protein family and an attractive cancer therapeutic target. In this study, the crystal structure of the human K-Ras­(G12D) mutant was determined in complex with GDP and KRpep-2d at 1.25 Å resolution. This structure revealed that the peptide binds near Switch II and allosterically blocks protein–protein interactions with the guanine nucleotide exchange factor. This discovery of a unique binding pocket provides valuable information that will facilitate the design of direct Ras inhibitors.