Minor component of the RACK1 regulatory proteins that play a role in multiple signal transduction pathways. Involved in multiple hormone responses and developmental processes (PubMed:18947417). MAPK cascade scaffolding protein involved in the protease IV and ArgC signaling pathway but not the flg22 pathway (PubMed:25731164). Homodimer and heterodimer with RACK1A or RACK1B (Probable). Interacts with GB1, MEKK1, MKK4, MKK5, MPK3 and MPK6, but not with GPA1 or MPK4 (PubMed:25731164). Widely expressed. No visible phenotype under normal growth condition. Belongs to the WD repeat G protein beta family. Ribosomal protein RACK1 subfamily.