"Stimulates the exchange of guanyl nucleotides by a GTPase. Under normal cellular physiological conditions, the concentration of GTP is higher than that of GDP, favoring the replacement of GDP by GTP in association with the GTPase [goid 5085] [pmid 15247254] [evidence IDA]; Stimulates the exchange of guanyl nucleotides by a GTPase of the Ran family. Under normal cellular physiological conditions, the concentration of GTP is higher than that of GDP, favoring the replacement of GDP by GTP in association with the GTPase [goid 5087] [pmid 11586298] [evidence NAS]; Interacting selectively with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules) [goid 5515] [evidence IEA]; Interacting selectively with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules) [goid 5515] [pmid 17239822] [evidence IPI]; Interacting selectively with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules) [goid 5515] [evidence IEA]; Stimulates the exchange of guanyl nucleotides by a GTPase of the Rab family. Under normal cellular physiological conditions, the concentration of GTP is higher than that of GDP, favoring the replacement of GDP by GTP in association with the GTPase [goid 17112] [pmid 12837691] [evidence IDA]; Interacting selectively with Rab protein, any member of the Rab subfamily of the Ras superfamily of monomeric GTPases [goid 17137] [pmid 16670179] [evidence NAS]; Interacting selectively with Rab protein, any member of the Rab subfamily of the Ras superfamily of monomeric GTPases [goid 17137] [pmid 15247254] [evidence IDA]; Stimulates the exchange of guanyl nucleotides by a GTPase of the Rac family. Under normal cellular physiological conditions, the concentration of GTP is higher than that of GDP, favoring the replacement of GDP by GTP in association with the GTPase [goid 30676] [pmid 16049005] [evidence IDA]; Interacting selectively with an identical protein to form a homodimer [goid 42803] [pmid 15247254] [evidence IPI]; Increases the activity of a protein serine/threonine kinase [goid 43539] [pmid 16049005] [evidence IDA]"