Comprehensive Protein Interactome Analysis of a Key XXXX : Detection of Novel Stress Granule Proteins.

@entity1 @entity62121 @entity48954 @entity71803 @entity71804 @entity25933 @entity2100 @entity42364 @entity71805
UNASSIGNED: @entity25933 ( @entity25933 / @entity48954 ) is a @entity1 @entity71803 with central roles in mRNA decay and translation repression. To help our understanding of how @entity25933 performs these multiple functions, we conducted the first unbiased, large-scale study to map the @entity25933 -centric protein-protein interactome using immunoprecipitation and mass spectrometry. Using @entity25933 as bait, we identify a high-confidence and high-quality set of protein interaction partners which are enriched for functions in RNA metabolism and ribosomal proteins. The screen is highly specific, maximizing the number of true positives, as demonstrated by the validation of 81% (47/58) of the RNA-independent interactors through known functions and interactions. Importantly, we minimize the number of indirect interaction partners through use of a nuclease-based digestion to eliminate RNA. We describe eleven new interactors, including proteins involved in splicing which is an as-yet unknown role for @entity25933 . We validated and characterized in more detail the interaction of @entity25933 with Nuclear @entity2100 -interacting protein 2 ( @entity62121 ) and with two previously uncharacterized proteins, @entity71804 and @entity71805 (here referred to as granulin-1 and granulin-2, or GRAN1 and GRAN2). We show that @entity62121 , GRAN1, and GRAN2 are not P-body components, but re-localize to stress granules upon exposure to stress, suggesting a function in translation repression in the cellular stress response. Using a complementary analysis that resolved @entity25933 's multiple complex memberships, we further validated these interaction partners and the presence of splicing factors. As @entity25933 also interacts with the E3 SUMO ligase @entity42364 , we tested for and observed a significant enrichment of sumoylation amongst @entity25933 's interaction partners. Our results represent the most comprehensive screen for direct interaction partners of a key regulator of RNA life cycle and localization, highlighting new stress granule components and possible @entity25933 functions-many of which are likely conserved across eukaryotes.
