Thylakoid lumen If a protein is to be targeted to the thylakoid lumen, this may occur via four differently known routes that closely resemble bacterial protein transport mechanisms. The route that is taken depends upon the protein delivered to the stroma being in either an unfolded or metal-bound folded state. Both of which will still contain a thylakoid targeting sequence that is also cleaved upon entry to the lumen. While protein import into the stroma is ATP-driven, the pathway for metal-bound proteins in a folded state to the thylakoid lumen has been shown to be driven by a pH gradient.thumb|Pathways for proteins targeted to the thylakoid membrane in chloroplasts.
Thylakoid lumen If a protein is to be targeted to the thylakoid lu.men, this may occur via four differently known routes that closely resemble bacterial protein transport mecha,nisms The route that is taken depends upon the protein delivered to the stroma being in either an unfolded or metal-bound folded state. Both of which will still contain a thylakoid targeting sequence that is also cleaved upon entry to the lumen. While protein import into the s.troma is ATP-driven the pathway for metal-bound proteins in a folded state to the thylakoid lumen has been shown to be driven by a pH gradientthumb|Pathways for proteins targeted to the thylakoid membrane in chloroplasts.