The protein-protein interaction between two spliced leader trans-splicing factors is mediated by two interlinked α-helical domains.

SNA-1 and SNA-2 proteins are involved in spliced leader <i>trans</i> -splicing in <i>Caenorhabditis elegans</i> . They are components of the SL1 snRNP that donates the spliced leader 1 RNA which replaces the 5' end of most pre-mRNAs. SNA-1 and SNA-2 bind to each other, but the nature of their interaction is unclear. AlphaFold-Multimer predicts that the central region of SNA-1 and the C-terminal region of SNA-2 , each consisting of 3 α-helices, interlink to bring about the interaction between these proteins. Using yeast 2-hybrid assays we demonstrate that these regions are required and sufficient for this unusual mode of interaction between two proteins.