[1] Members of the superfamily are divided into families and subfamilies based on their structure, sequence and function.

The five main families are Ras, Rho, Ran, Rab and Arf GTPases.

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 WASP.

[3] The following is a list of human proteins belonging to the Ras superfamily:[1] Unclassified: