GTR1 was first identified in S. cerevisiae as a suppressor of a mutation in RCC1. Biochemical analysis revealed that Gtr1 is in fact a G protein of the Ras family. The RagA/B proteins are the human homologues of Gtr1. Included in this family is the human Rag C, a novel protein that has been shown to interact with RagA/B [1,2,3,4].

1: Putative GTP-binding protein, Gtr1, associated with the function of the Pho84 inorganic phosphate transporter in Saccharomyces cerevisiae. Bun-Ya M, Harashima S, Oshima Y; Mol Cell Biol 1992;12:2958-2966. PMID:1620108

2: Cloning of a novel family of mammalian GTP-binding proteins (RagA, RagBs, RagB1) with remote similarity to the Ras-related GTPases. Schurmann A, Brauers A, Massmann S, Becker W, Joost HG; J Biol Chem 1995;270:28982-28988. PMID:7499430

3: Saccharomyces cerevisiae putative G protein, Gtr1p, which forms complexes with itself and a novel protein designated as Gtr2p, negatively regulates the Ran/Gsp1p G protein cycle through Gtr2p. Nakashima N, Noguchi E, Nishimoto T; Genetics 1999;152:853-867. PMID:10388807

4: Novel G proteins, Rag C and Rag D, interact with GTP-binding proteins, Rag A and Rag B. Sekiguchi T, Hirose E, Nakashima N, Ii M, Nishimoto T; J Biol Chem 2001;276:7246-7257. PMID:11073942