Scaffolding protein involved in the recruitment, assembly and/or regulation of a variety of signaling molecules. Interacts with a wide variety of proteins and plays a role in many cellular processes. Component of the 40S ribosomal subunit involved in translational repression (PubMed:15340087). Involved in the initiation of the ribosome quality control (RQC), a pathway that takes place when a ribosome has stalled during translation, by promoting ubiquitination of a subset of 40S ribosomal subunits (By similarity). Binds to and stabilizes activated protein kinase C (PKC), increasing PKC-mediated phosphorylation. May recruit activated PKC to the ribosome, leading to phosphorylation of EIF6. Inhibits the activity of SRC kinases including SRC, LCK and YES1. Inhibits cell growth by prolonging the G0/G1 phase of the cell cycle. Enhances phosphorylation of BMAL1 by PRKCA and inhibits transcriptional activity of the BMAL1-CLOCK heterodimer. Facilitates ligand-independent nuclear translocation of AR following PKC activation, represses AR transactivation activity and is required for phosphorylation of AR by SRC. Modulates IGF1R-dependent integrin signaling and promotes cell spreading and contact with the extracellular matrix. Involved in PKC-dependent translocation of ADAM12 to the cell membrane. Promotes the ubiquitination and proteasome-mediated degradation of proteins such as CLEC1B and HIF1A. Required for VANGL2 membrane localization, inhibits Wnt signaling, and regulates cellular polarization and oriented cell division during gastrulation. Required for PTK2/FAK1 phosphorylation and dephosphorylation. Regulates internalization of the muscarinic receptor CHRM2. Promotes apoptosis by increasing oligomerization of BAX and disrupting the interaction of BAX with the anti-apoptotic factor BCL2L. Inhibits TRPM6 channel activity. Regulates cell surface expression of some GPCRs such as TBXA2R. Plays a role in regulation of FLT1-mediated cell migration. Involved in the transport of ABCB4 from the Golgi to the apical bile canalicular membrane. Monomer; also forms homodimers and homooligomers (By similarity). Interacts with CPNE3 (By similarity). May interact with ABCB4 (By similarity) Component of the small (40S) ribosomal subunit (PubMed:15340087). Interacts with LARP4. Interacts with LARP4B. Interacts with PKD2L1 (By similarity). Binds SLC9A3R1. Forms a ternary complex with TRIM63 and PRKCE. Interacts with HABP4, KRT1 and OTUB1. Interacts with SRC (via SH2 domain); the interaction is enhanced by tyrosine phosphorylation of RACK1. Recruited in a circadian manner into a nuclear complex which also includes BMAL1 and PRKCA. Interacts with AR. Interacts with IGF1R but not with INSR. Interacts with ADAM12. Interacts with CLEC1B (via N-terminal region) and with HIF1A; the interaction promotes their degradation. Interacts with RHOA; this enhances RHOA activation and promotes cell migration. Interacts with CHRM2; the interaction regulates CHRM2 internalization. Interacts with TRPM6 (via kinase domain). Interacts with PTK2/FAK1; required for PTK2/FAK1 phosphorylation and dephosphorylation. Interacts with FLT1. Interacts with HRAS. Recruited to the plasma membrane through interaction with KRT1 which binds to membrane-bound ITGB1. Also associated with the membrane in oncogene-transformed cells. PKC activation induces translocation from the perinuclear region to the cell periphery (By similarity). In the brain, detected mainly in cell bodies and dendrites with little expression in axonal fibers or nuclei (By similarity). The 7 WD repeats mediate protein-protein interactions with binding partners. Phosphorylated on Tyr-228 and/or Tyr-246 by SRC. This is required for binding to SRC (By similarity). Belongs to the WD repeat G protein beta family. Ribosomal protein RACK1 subfamily.