InterPro domain: IPR009771

This entry represents RIC1 (Ribosomal control protein1) and has been identified in yeast as a Golgi protein involved in retrograde transport to the cis-Golgi network. It forms a heterodimer with Rgp1 and functions as a guanyl-nucleotide exchange factor [ 1 ] which activates YPT6 by exchanging bound GDP for free GTP. RIC1 is thereby required for efficient fusion of endosome-derived vesicles with the Golgi. The RIC1-RGP1 complex participates in the recycling of SNC1, presumably by mediating fusion of endosomal vesicles with the Golgi compartment and may also be indirectly involved in the transcription of both ribosomal protein genes and ribosomal RNA [ 2 , 2 , 3 ].

1. Ric1p and Rgp1p form a complex that catalyses nucleotide exchange on Ypt6p. EMBO J. 19, 4885-94
2. An effector of Ypt6p binds the SNARE Tlg1p and mediates selective fusion of vesicles with late Golgi membranes. EMBO J. 20, 5991-8
3. Ric1p and the Ypt6p GTPase function in a common pathway required for localization of trans-Golgi network membrane proteins. Mol. Biol. Cell 12, 13-26