Distinct functions for the paralogous RBM41 and U11/U12-65K proteins in the minor spliceosome.
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The human RBM41 RRM binds the 3'-terminal stem-loops of U12 and U6atac snRNAs in vitro, with about 2-fold weaker affinity than the U11/U12-65K C-terminal RRM.
"the RBM41 RRM has a low micromolar affinity to both U12 (Kd= 2.14 μM) and U6atac hairpins (Kd= 3.78 μM; Figure 2D)"
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RBM41 partitions into the U12 mono-snRNP, separately from 65K in the U11/U12 di-snRNP.
"RBM41 peak co-migrated with the U12 mono-snRNP"
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RBM41 associates with excised U12-type intron lariats and, through its N-terminal region, with DHX8.
"RBM41 preferentially co-immunoprecipitated U12-type but not U2-type intron lariats"
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Endogenous RBM41 localizes to Cajal bodies.
"we found that endogenous RBM41 localizes to Cajal bodies, as shown by colocalization with coilin-GFP in HEK293 cells"
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RBM41 knockout HEK293 cells are viable but show altered 3' splice site usage at a subset of U12-type introns.
"suggesting that the loss of RBM41 has a weak, but nevertheless statistically significant effect on the splicing of a subset of U12-type introns"
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Phylogenetic profiling links RBM41 to minor spliceosome components across eukaryotes.
"three minor spliceosome-specific proteins, CENATAC, U11-48K (SNRP48) and U11/U12-31K (ZCRB1) were found among the proteins showing the strongest co-occurrence with RBM41"