Tripartite motif-containing protein 21, also known as E3 ubiquitin-protein ligase TRIM21, is a protein that in humans is encoded by the TRIM21gene. Alternatively spliced transcript variants for this gene have been described but the full-length nature of only one has been determined. It is expressed in most human tissues.
RoSSA interacts with autoantigens in patients with Sjögren's syndrome and systemic lupus erythematosus. In addition, the inability for lupus-prone macrophages to degrade immune complexes in the lysosome results in the leakage of autoantibodies into the cytosol that can bind to TRIM21 and enhance NF-κB signaling.
TRIM21 can be used to knockout specific proteins with their corresponding antibodies, a method known as Trim-Away. In this assay, TRIM21 and antibodies are delivered into cells through electroporation, and the targeted protein is degraded within a few minutes.
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