Ypp1 colocalizes with Stt4 at static cortical structures at the PM. (A) Cells expressing Ypp1-GFP were grown at 26°C and examined by fluorescence microscopy. Cells shown are representative of over 200 cells observed. Arrows show regions of highly concentrated Ypp1-GFP. Bar, 4 μm. (B) Cells coexpressing GFP-Stt4 and Ypp1-mCherry were grown at 26°C and examined by confocal microscopy. As previously reported (Audhya and Emr, 2002), GFP-Stt4 localizes to cortical patches on the PM (top left) and with a similar distribution as Ypp1-mCherry (top right). An overlay of the two images (bottom left) shows overlap of the fluorescent patches. Arrows indicate regions of the most conspicuous colocalization. Bar, 4 μm. (C) Schematic representation of Stt4, Ygr198w (Ypp1), and the Ypp1 human homologue TTC7a (available from GenBank/EMBL/DDBJ under accession no. NM_020458). Stt4 is a 215-kD protein with a lipid kinase unique domain (LKU) and a PtdIns 4-kinase domain (PI4K) as its only recognizable motifs. Ypp1 is a 95-kD protein encompassing multiple TPR domains and with conserved homologues in higher species. The schematics are not to scale.