Ras Superfamily

The Ras superfamily is a protein superfamily of small GTPases, which are all related, to a degree, to the Ras protein subfamily (the key human members of which are KRAS, NRAS, and HRAS).

There are more than a hundred proteins in the Ras superfamily. Based on structure, sequence and function, the Ras superfamily is divided into eight main families, each of which is further divided into subfamilies: Ras, Rad, Rab, Rap, Ran, Rho, Rheb, Rit, and Arf. Miro is a recent contributor to the superfamily.

Each subfamily shares the common core G domain, which provides essential GTPase and nucleotide exchange activity.

The surrounding sequence helps determine the functional specificity of the small GTPase, for example the 'Insert Loop', common to the Rho subfamily, specifically contributes to binding to effector proteins such as IQGAP and WASP.

The Ras family is generally responsible for cell proliferation, Rho for cell morphology, Ran for nuclear transport and Rab and Arf for vesicle transport.