Ras (protein)

Ras (protein)

The Ras protein is a protein that is used by all cellular life forms to receive signals from outside the cell. The term "Ras" is derived from "rat sarcoma", as it was first identified in rats with sarcomas. It is a member of the G protein family and is involved in transmitting signals within cells (cellular signal transduction).

Ras proteins function as binary molecular switches, alternating between an inactive "off" state and an active "on" state. This switch is triggered by signals from outside the cell, which cause a change in the protein's shape. When Ras is 'turned on' by incoming signals, it alerts the cell to important changes in its environment that may require a response.

Structure and function

Ras proteins are monomeric G proteins that bind guanosine triphosphate (GTP) and guanosine diphosphate (GDP). They have a molecular weight of approximately 21 kDa. The proteins are attached to the cell membrane by a series of modifications to their C-terminus, which allow them to interact with the inner surface of the cell membrane.

Ras proteins play a crucial role in several cellular processes, including cell division, cell differentiation, and cell survival. They do this by activating a number of signal transduction pathways, most notably the MAPK/ERK pathway and the PI3K/AKT/mTOR pathway.

Role in disease

Mutations in the genes that encode Ras proteins can lead to the production of permanently activated Ras, which in turn can cause uncontrolled cell division and lead to the formation of tumors. Such mutations are found in 20-25% of all human tumors, making Ras one of the most common oncogenes.

See also

• G protein
• Signal transduction
• Oncogene