RNA recognition motif 1 (RRM1) found in nucleolysin TIA-1 isoform p40 (p40-TIA-1) and similar proteins
This subgroup corresponds to the RRM1 of TIA-1, the 40-kDa isoform of T-cell-restricted intracellular antigen-1 (TIA-1) and a cytotoxic granule-associated RNA-binding protein mainly found in the granules of cytotoxic lymphocytes. TIA-1 can be phosphorylated by a serine/threonine kinase that is activated during Fas-mediated apoptosis, and functions as the granule component responsible for inducing apoptosis in cytolytic lymphocyte (CTL) targets. It is composed of three N-terminal highly homologous RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a glutamine-rich C-terminal auxiliary domain containing a lysosome-targeting motif. TIA-1 interacts with RNAs containing short stretches of uridylates and its RRM2 can mediate the specific binding to uridylate-rich RNAs.