KRAS (Kirsten rat sarcoma virus) is a gene that provides instructions for making a protein called K-Ras, a part of the RAS/MAPK pathway. The protein relays signals from outside the cell to the cell's nucleus. These signals instruct the cell to grow and divide (proliferate) or to mature and take on specialized functions (differentiate). It is called KRAS because it was first identified as a viral oncogene in the Kirsten RAt Sarcoma virus. The oncogene identified was derived from a cellular genome, so KRAS, when found in a cellular genome, is called a proto-oncogene.

The K-Ras protein is a GTPase, a class of enzymes which convert the nucleotide guanosine triphosphate (GTP) into guanosine diphosphate (GDP). In this way the K-Ras protein acts like a switch that is turned on and off by the GTP and GDP molecules. To transmit signals, it must be turned on by attaching (binding) to a molecule of GTP. The K-Ras protein is turned off (inactivated) when it converts the GTP to GDP. When the protein is bound to GDP, it does not relay signals to the nucleus. KRAS acts as a molecular on/off switch, using protein dynamics. Once it is allosterically activated, it recruits and activates proteins necessary for the propagation of growth factors, as well as other cell signaling receptors like c-Raf and PI 3-kinase. In some cancers, KRAS is an interesting therapeutic target. Here you can see the structure of human KRAS in complex with an allosteric inhibitor. Note the location of the drug close to the ATP-binding pocket (PDB code: 8AZV)

#molecularart ... #immolecular ... #cancer ... #KRAS .. #inhibitor ... #kinase ... #allosteric ... #xray

Structure rendered with @proteinimaging and depicted with @corelphotopaint