Editing Protein targeting (section)

==== Stroma ====
Targeting to the stroma requires the preprotein to have a stromal import sequence that is recognized by the Tic complex of the inner envelope upon being translocated from the outer envelope by the Toc complex. The Tic complex is composed of at least five different Tic proteins that are required to form the translocation channel across the inner envelope.<ref>{{Cite journal |last=Gutensohn M, Fan E, Frielingsdorf S, Hanner P, Hou B, Hust B, Klosgen R |date=2005 |title=Toc, Tic, Tat et al.: structure and function of protein transport machineries in chloroplasts |url=https://pubmed.ncbi.nlm.nih.gov/16386331/ |journal=Journal of Plant Physiology |volume=163 |issue=3 |pages=333–347 |doi=10.1016/j.jplph.2005.11.009 |pmid=16386331 |via=PubMed}}</ref> Upon being delivered to the stroma, the stromal import sequence is cleaved off via a signal peptidase. This delivery process to the stroma is currently known to be driven by [[ATP hydrolysis]] via stromal [[Heat shock protein|HSP]] chaperones, instead of the transmembrane [[electrochemical gradient]] that is established in mitochondria to drive protein import.<ref name="Soll J, Schleiff E-2004" /> Further intra-chloroplast sorting depends on additional target sequences such as those designated to the [[Thylakoid|thylakoid membrane]] or the [[Thylakoid|thylakoid lumen]].