Tudor-SN interacts with and co-localizes with G3BP in stress granules under stress conditions.

SGs are mRNA containing cytoplasmic structures that are assembled in response to stress. Tudor-SN protein is a ubiquitously expressed protein. Here, Tudor-SN protein was found to physiologically interact with G3BP, which is the marker and effector of SG. The kinetics of the assembly of SGs in the living cells demonstrated that Tudor-SN co-localizes with G3BP and is recruited to the same SGs in response to different stress stimuli. Knockdown of endogenous Tudor-SN did not inhibit the formation of SGs, but retarded the aggregation of small SGs into large SGs. Thus Tudor-SN may not be an initiator as essential as G3BP for the formation of SGs, but affects the aggregation of SGs. These findings identify Tudor-SN as a novel component of SGs.