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Suprachiasmatic nucleus circadian oscillatory protein, a novel binding partner of K-Ras in the membrane rafts, negatively regulates MAPK pathway.

Authors: Shimizu, K  Okada, M  Nagai, K  Fukada, Y 
Citation: Shimizu K, etal., J Biol Chem. 2003 Apr 25;278(17):14920-5. Epub 2003 Feb 19.
Pubmed: (View Article at PubMed) PMID:12594205
DOI: Full-text: DOI:10.1074/jbc.M213214200

Suprachiasmatic nucleus circadian oscillatory protein (SCOP) is a member of the leucine-rich repeat (LRR)-containing protein family. In addition to circadian expression in the rat hypothalamic suprachiasmatic nucleus, SCOP is constitutively expressed in neurons throughout the rat brain. Here we found that a substantial amount of SCOP was localized in the brain membrane rafts, in which only K-Ras was abundant among Ras isoforms. SCOP interacted directly through its LRR domain with a subset of K-Ras in the guanine nucleotide-free form that was present in the raft fraction. This interaction interfered with the binding of added guanine nucleotide to K-Ras in vitro. A negative regulatory role of SCOP for K-Ras function was examined in PC12 cell lines stably overexpressing SCOP or its deletion mutants. Overexpression of full-length SCOP markedly down-regulated ERK1/ERK2 activation induced by depolarization or phorbol ester stimulation, and this inhibitory effect of overexpressed SCOP was dependent on its LRR domain. These results strongly suggest that SCOP negatively regulates K-Ras signaling in the membrane rafts, identifying a novel mechanism for regulation of the Ras-MAPK pathway.

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RGD Object Information
RGD ID: 1581766
Created: 2006-10-24
Species: All species
Last Modified: 2006-10-24
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.