Small ribosomal subunit protein RACK1

RACK1 (small ribosomal subunit protein RACK1) is a multifunctional scaffolding protein of 317 amino acids that acts as a platform for recruiting and regulating diverse signaling molecules (UniProt: P63244). It is a component of the 40S ribosomal subunit involved in translational repression and ribosome quality control, where it promotes ubiquitination of stalled ribosomal subunits. Beyond its ribosomal functions, RACK1 modulates protein kinase C signaling, cell cycle progression, circadian transcription, and apoptosis through interactions with numerous substrates including PKC, SRC kinases, BMAL1, and BAX/BCL2L.

RACK1 participates in multiple cellular pathways spanning translation, signal transduction, cell migration, and membrane trafficking (UniProt: P63244). The protein also mediates host responses to microbial infection, including interactions with bacterial virulence factors and contributions to viral translation. No underlying disease mutations are catalogued in UniProt, but the protein's broad regulatory roles suggest involvement in multiple pathological contexts.

In Alzheimer's disease, RACK1 is significantly upregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of 0.46. This upregulation was detected via TMT-labeled proteomics across subcellular fractions of human brain samples, suggesting a potential role in AD pathophysiology, though the mechanistic contribution remains to be established.