All alpha-helical domain that accelerates the GTPase activity of Ras, thereby "switching" it into an "off" position.

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2: The interaction of Ras with GTPase-activating proteins. Wittinghofer A, Scheffzek K, Ahmadian MR; FEBS Lett 1997;410:63-67. PMID:9247124

3: The neurofibromatosis type 1 gene encodes a protein related to GAP. Xu GF, O'Connell P, Viskochil D, Cawthon R, Robertson M, Culver M, Dunn D, Stevens J, Gesteland R, White R, et al; Cell 1990;62:599-608. PMID:2116237