Guanine nucleotide-binding protein that plays a crucial role in the cellular response to amino acid availability through regulation of the mTORC1 signaling cascade (  ). Forms heterodimeric Rag complexes with RagC/RRAGC or RagD/RRAGD and cycles between an inactive GDP-bound and an active GTP-bound form: RagA/RRAGA is in its active form when GTP-bound RagA/RRAGA forms a complex with GDP-bound RagC/RRAGC (or RagD/RRAGD) and in an inactive form when GDP-bound RagA/RRAGA heterodimerizes with GTP-bound RagC/RRAGC (or RagD/RRAGD) (  , ). In its GTP-bound active form, promotes the recruitment of mTORC1 to the lysosomes and its subsequent activation by the GTPase RHEB ( , ). Involved in the RCC1/Ran-GTPase pathway . May play a direct role in a TNF-alpha signaling pathway leading to induction of cell death .
(Microbial infection) May alternatively act as a cellular target for adenovirus E3-14.7K, an inhibitor of TNF-alpha functions, thereby affecting cell death.
Subcellular locations: Cytoplasm, Nucleus, Lysosome membrane
Predominantly cytoplasmic (, ). Recruited to the lysosome surface by the Ragulator complex ( ). May shuttle between the cytoplasm and nucleus, depending on the bound nucleotide state (, ). Colocalizes in vivo with adenovirus E3-14.7K mainly to the cytoplasm especially near the nuclear membrane and in discrete foci on or near the plasma membrane .
Ubiquitously expressed with highest levels of expression in skeletal muscle, heart, and brain.