Fig.·4. Colocalization of Arp2p with mitochondria in yeast. Budding yeast cells expressing a fusion protein consisting of the mitochondrial signal sequence of citrate synthase 1 fused to GFP (CS1-GFP) were grown to mid-log phase, fixed with paraformaldehyde and stained for Arp2p using an antibody raised against a conserved peptide sequence found in Arp2p, but not in actin or any other actin-related protein (Moreau et al., 1996). Green, mitochondria visualized using CS1-GFP; red, Arp2p visualized by indirect immunofluorescence. Bar, 1·µm.