5y3a
Crystal structure of Ragulator complex (p18 49-161)
Structural highlights
FunctionLTOR1_HUMAN As part of the Ragulator complex it is involved in amino acid sensing and activation of mTORC1, a signaling complex promoting cell growth in response to growth factors, energy levels, and amino acids. Activated by amino acids through a mechanism involving the lysosomal V-ATPase, the Ragulator functions as a guanine nucleotide exchange factor activating the small GTPases Rag. Activated Ragulator and Rag GTPases function as a scaffold recruiting mTORC1 to lysosomes where it is in turn activated. LAMTOR1 is directly responsible for anchoring the Ragulator complex to membranes. Also required for late endosomes/lysosomes biogenesis it may regulate both the recycling of receptors through endosomes and the MAPK signaling pathway through recruitment of some of its components to late endosomes. May be involved in cholesterol homeostasis regulating LDL uptake and cholesterol release from late endosomes/lysosomes. May also play a role in RHOA activation.[1] [2] [3] [4] Publication Abstract from PubMedAmino acid-dependent activation of the mechanistic target of rapamycin complex 1 (mTORC1) is mediated by Rag GTPases, which are recruited to the lysosome by the Ragulator complex consisting of p18, MP1, p14, HBXIP and C7orf59; however, the molecular mechanism is elusive. Here, we report the crystal structure of Ragulator, in which p18 wraps around the MP1-p14 and C7orf59-HBXIP heterodimers and the interactions of p18 with MP1, C7orf59, and HBXIP are essential for the assembly of Ragulator. There are two binding sites for the Roadblock domains of Rag GTPases: helix alpha1 of p18 and the two helices side of MP1-p14. The interaction of Ragulator with Rag GTPases is required for their cellular co-localization and can be competitively inhibited by C17orf59. Collectively, our data indicate that Ragulator functions as a scaffold to recruit Rag GTPases to lysosomal membrane in mTORC1 signaling. Structural basis for Ragulator functioning as a scaffold in membrane-anchoring of Rag GTPases and mTORC1.,Zhang T, Wang R, Wang Z, Wang X, Wang F, Ding J Nat Commun. 2017 Nov 9;8(1):1394. doi: 10.1038/s41467-017-01567-4. PMID:29123114[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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