Rpg1p/Tif32p, a subunit of translation initiation factor 3, interacts withactin-associated protein Sla2p

The yeast two-hybrid system was used to screen for proteins that interact i n vivo with Saccharomyces cerevisiae Rpg1p/Tif32p, the large subunit of the translation initiation factor 3 core complex (eIF3), Eight positive clones encoding portions of the SLA2/END4/MOP2 gene were isolated. They overlappe d in the region of amino acids 318-550, Subsequent deletion analysis of S1a 2p showed that amino acids 318-373 were essential for the two-hybrid protei n-protein interaction. The N-terminal part of Rpg1p (aa 1-615) was essentia l and sufficient for the Rpg1p-Sla2p interaction. A coimmunoprecipitation a ssay provided additional evidence for the physical interaction of Rp1p/Tif3 2p with Sla2p in vivo. Using immunofluorescence microscopy, Rpg1p and Sla2p proteins were colocalized at the patch associated with the tip of emerging bud, Considering the essential role of Rpg1p as the large subunit of the e IF3 core complex and the association of Sla2p with the actin cytoskeleton, a putative role of the Rpg1p-Sla2p interaction in localized translation is discussed. (C) 2001 Academic Press.