What does a RAS gene do?
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Many structures for Ras have been solved, showing the different conformational states in the signaling cycle. The two shown here capture Ras with GTP and GDP, in the on and off states (PDB entries 5p21 and 4q21 ). Comparison of these structures revealed that two loops (in green) near the nucleotide change conformation. This is the signal that is recognized by the effector proteins that transmit the signal. Structures have also revealed the importance of glutamine 61, which positions a water molecule to perform the cleavage reaction. This glutamine is often mutated in cancer cells, so the GTP is never cleaved and the protein is always turned on. To see several other structures that show the action of this amino acid, click on the image for an interactive Jmol. Show
The word Ras comes from a contraction of Rat sarcoma, the tumor where the first gene of the family was identified, as part of the genome of a retrovirus isolated from a carcinogenesis protocol. CharacteristicsStructureThe Ras genes, strictly speaking, are only a small group of a large family of related genes (the Ras superfamily) that perform a host of important cellular functions including signal transduction (Ras, Ral, Rho), cytoskeletal regulation (Rho), vesicle transport (Rab), and nuclear-cytoplasmic transport (Ran). The Ras genes more relevant for human cancer are: H-ras, K-ras, and N-ras and they will be the subject of this essay. H-ras was initially isolated from the Harvey sarcoma virus. K-ras from the Kirsten sarcoma virus and N-ras was isolated by DNA-mediated gene transfer from a human neuroblastoma cell line. In humans, they are located in chromosome 11p15, H-ras; 12p12, K-ras; and 1p22, N-ras. These three genes code for very similar proteins of 189 amino... This is a preview of subscription content, access via your institution. Buying optionsChapter EUR 29.95 Price includes VAT (Singapore)
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Learn about institutional subscriptions RAS Genes. Fig. 1  RAS Genes. Fig. 2 RAS Genes. Fig. 3 Bourne H, Sanders DA, McCormick F (1990) The GTPase superfamily: conserved structure and molecular mechanism. Nature 349:117–127 CrossRef Google Scholar Malumbres M, Barbacid M (2003) RAS oncogenes: the first 30 years. Nat Rev Cancer 3:459–465 CrossRef CAS PubMed Google Scholar Malumbres M, Pellicer A (1998) Ras pathways to cell cycle control and cell transformation. Front Biosci 3:d887–d912 CrossRef CAS PubMed Google Scholar Schubbert S, Shannon K, Bollag G (2007) Hyperactive Ras in developmental disorders and cancer. Nat Rev Cancer 7:295–308 CrossRef CAS PubMed Google Scholar Download references Author informationAuthors and Affiliations
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Corresponding authorCorrespondence to Angel Pellicer . Editor informationEditors and Affiliations
Rights and permissionsReprints and Permissions Copyright information© 2011 Springer-Verlag Berlin Heidelberg About this entryCite this entryPellicer, A. (2011). RAS Genes. In: Schwab, M. (eds) Encyclopedia of Cancer. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-16483-5_4951 What does the gene RAS code for?Ras genes encode proteins that can cause cancer (or become oncogenic) when mutated. All Ras proteins are GTPases which act as molecular switches in the cell, regulating signaling pathways and other interactions. There are three Ras proteins, which are ubiquitously expressed in the body.
Is the ras gene a tumor suppressor?The Ras Effector RASSF2 Is a Novel Tumor-Suppressor Gene in Human Colorectal Cancer.
Does the ras gene stimulate the cell cycle?Indeed, oncogenic RAS can promote cell cycle progression by deregulating anti-growth signalling pathways through the suppression of cyclin-dependent kinase inhibitors (CKIs), such as p27 and p21, which would otherwise associate with and inhibit cyclin-dependent kinases (CDKs).
What is the role of RAS in signaling pathways?Ras signaling is an important intracellular signaling pathway that plays a role in cellular proliferation and differentiation, survival, and gene expression. Ras oncoprotein has also been implicated in the development of cancer by either having increased intensity or prolonged signaling mechanism.
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