Higher plant chloroplasts possess at least four different pathways for pro-tein translocation across and protein integration into the thylakoid mem-branes. It is of interest with respect to plastid evolution, which pathways have been retained as a relic from the cyanobacterial ancestor (‘conserva-tive sorting’), which ones have been kept but modified, and which ones were developed at the organelle stage, . are eukaryotic achievements as (largely) the Toc and Tic translocons for envelope import of cytosolic pre-cursor proteins. .
