Figure 1
From: The physical and functional borders of transit peptide-like sequences in secondary endosymbionts
Schematic depiction of the plastid architecture of P. tricornutum. The complex plastid is surrounded by four membranes (counted from outside to inside) with the outermost one being continuous with the endoplasmic reticulum. The cER is studded with ribosomes facilitating co-translational import of plastid precursors across the 1st membrane into the ER lumen. The candidates for translocons of the subsequent membranes (not shown) of secondary plastids with red algal ancestry have been elucidated recently [see 30, 31, 32, 33, 38, 40, 41, 42]. cER, chloroplast endoplasmic reticulum; PPC, periplastid compartment; IMS, intermembrane space.