Defining the Caprin-1 Interactome in Unstressed and Stressed Conditions

J Proteome Res. 2021 Jun 4;20(6):3165-3178. doi: 10.1021/acs.jproteome.1c00016. Epub 2021 May 3.


Cytoplasmic stress granules (SGs) are dynamic foci containing translationally arrested mRNA and RNA-binding proteins (RBPs) that form in response to a variety of cellular stressors. It has been debated that SGs may evolve into cytoplasmic inclusions observed in many neurodegenerative diseases. Recent studies have examined the SG proteome by interrogating the interactome of G3BP1. However, it is widely accepted that multiple baits are required to capture the full SG proteome. To gain further insight into the SG proteome, we employed immunoprecipitation coupled with mass spectrometry of endogenous Caprin-1, an RBP implicated in mRNP granules. Overall, we identified 1543 proteins that interact with Caprin-1. Interactors under stressed conditions were primarily annotated to the ribosome, spliceosome, and RNA transport pathways. We validated four Caprin-1 interactors that localized to arsenite-induced SGs: ANKHD1, TALIN-1, GEMIN5, and SNRNP200. We also validated these stress-induced interactions in SH-SY5Y cells and further determined that SNRNP200 also associated with osmotic- and thermal-induced SGs. Finally, we identified SNRNP200 in cytoplasmic aggregates in amyotrophic lateral sclerosis (ALS) spinal cord and motor cortex. Collectively, our findings provide the first description of the Caprin-1 protein interactome, identify novel cytoplasmic SG components, and reveal a SG protein in cytoplasmic aggregates in ALS patient neurons. Proteomic data collected in this study are available via ProteomeXchange with identifier PXD023271.

Keywords: Caprin-1; RNA binding proteins; amyotrophic lateral sclerosis; cytoplasmic granules; cytoplasmic inclusions; mass spectrometry; protein−protein interactions; proteomics; stress granules.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytoplasmic Granules*
  • DNA Helicases*
  • Humans
  • Poly-ADP-Ribose Binding Proteins
  • Proteomics
  • RNA Helicases / genetics
  • RNA Recognition Motif Proteins
  • RNA-Binding Proteins / genetics


  • ANKHD1 protein, human
  • Poly-ADP-Ribose Binding Proteins
  • RNA Recognition Motif Proteins
  • RNA-Binding Proteins
  • DNA Helicases
  • G3BP1 protein, human
  • RNA Helicases