SecA homolog in protein transport within chloroplasts: evidence for endosymbiont-derived sorting

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Science  04 Nov 1994:
Vol. 266, Issue 5186, pp. 796-798
DOI: 10.1126/science.7973633


The SecA protein is an essential, azide-sensitive component of the bacterial protein translocation machinery. A SecA protein homolog (CPSecA) now identified in pea chloroplasts was purified to homogeneity. CPSecA supported protein transport into thylakoids, the chloroplast internal membrane network, in an azide-sensitive fashion. Only one of three pathways for protein transport into thylakoids uses the CPSecA mechanism. The use of a bacteria-homologous mechanism in intrachloroplast protein transport provides evidence for conservative sorting of proteins within chloroplasts.

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