6e6h
NRAS G13D bound to GppNHp (N13GNP)NRAS G13D bound to GppNHp (N13GNP)
Structural highlights
Disease[RASN_HUMAN] Defects in NRAS are a cause of juvenile myelomonocytic leukemia (JMML) [MIM:607785]. JMML is a pediatric myelodysplastic syndrome that constitutes approximately 30% of childhood cases of myelodysplastic syndrome (MDS) and 2% of leukemia. Defects in NRAS are the cause of Noonan syndrome type 6 (NS6) [MIM:613224]. A syndrome characterized by facial dysmorphic features such as hypertelorism, a downward eyeslant and low-set posteriorly rotated ears. Other features can include short stature, a short neck with webbing or redundancy of skin, cardiac anomalies, deafness, motor delay and variable intellectual deficits.[1] Defects in NRAS are the cause of autoimmune lymphoproliferative syndrome type 4 (ALPS4) [MIM:614470]. A disorder of apoptosis, characterized by chronic accumulation of non-malignant lymphocytes, defective lymphocyte apoptosis, and an increased risk for the development of hematologic malignancies.[2] Function[RASN_HUMAN] Ras proteins bind GDP/GTP and possess intrinsic GTPase activity. Publication Abstract from PubMedRas GTPases are mutated at codons 12, 13, and 61, with different frequencies in KRas, HRas, and NRas and in a cancer-specific manner. The G13D mutant appears in 25% of KRas-driven colorectal cancers, while observed only rarely in HRas or NRas. Structures of Ras G13D in the three isoforms show an open active site, with adjustments to the D13 backbone torsion angles and with disconnected switch regions. KRas G13D has unique features that destabilize the nucleotide-binding pocket. In KRas G13D bound to GDP, A59 is placed in the Mg(2+) binding site, as in the HRas-SOS complex. Structure and biochemistry are consistent with an intermediate level of KRas G13D bound to GTP, relative to wild-type and KRas G12D, observed in genetically engineered mouse models. The results explain in part the elevated frequency of the G13D mutant in KRas over the other isoforms of Ras. Isoform-Specific Destabilization of the Active Site Reveals a Molecular Mechanism of Intrinsic Activation of KRas G13D.,Johnson CW, Lin YJ, Reid D, Parker J, Pavlopoulos S, Dischinger P, Graveel C, Aguirre AJ, Steensma M, Haigis KM, Mattos C Cell Rep. 2019 Aug 6;28(6):1538-1550.e7. doi: 10.1016/j.celrep.2019.07.026. PMID:31390567[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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