HRAS
GTPase HRas, the "Harvey Rat sarcoma viral oncogene homolog", also known as transforming protein p21 is an enzyme that in humans is encoded by the HRAS gene. The HRAS gene is located on the short (p) arm of chromosome 11 at position 15.5, from base pair 522,241 to base pair 525,549. HRas is a small G protein in the Ras subfamily of the Ras superfamily of small GTPases. Once bound to guanosine triphosphate, H-Ras will activate a Raf kinase like c-Raf, the next step in the MAPK/ERK pathway.
As its name suggests, the gene was initially discovered in the Harvey rat sarcoma virus as a viral oncogene (Harvey murine sarcoma virus, Gammaretrovirus Hamursar). The gene in this virus was later discovered to closely resemble a cellular gene found in many animals; as a result, it was deduced that the virus incorporated the cellular gene into its genome in the past, leading it down the route of becoming an oncovirus. Incorporation of cellular genes happens regularly in retroviruses; when a key regulatory gene such as HRAS is incorporated, it may become oncogenic as the virus evolves for greater fitness. The benign version in the cellular genome is not directly cancerous, but further mutations can turn it cancerous. As a result, the cellular version is called a proto-oncogene.