Editing Chloroplast (section)

=== Amino acid synthesis ===

Chloroplasts alone make almost all of a plant cell's [[amino acids]] in their [[stroma (fluid)|stroma]]<ref name="Burgess-1989e" /> except the [[sulfur-containing amino acids|sulfur-containing]] ones like [[cysteine]] and [[methionine]].<ref name="Ferro-2002">{{cite journal | vauthors=Ferro M, Salvi D, Riviere-Rolland H, Vermat T, Seigneurin-Berny D, Grunwald D, Garin J, Joyard J, Rolland N | display-authors=6 | title=Integral membrane proteins of the chloroplast envelope: identification and subcellular localization of new transporters | journal=Proceedings of the National Academy of Sciences of the United States of America | volume=99 | issue=17 | pages=11487–92 | date=August 2002 | pmid=12177442 | pmc=123283 | doi=10.1073/pnas.172390399 | bibcode=2002PNAS...9911487F | doi-access=free }}</ref><ref name="Rolland-1992" /> Cysteine is made in the chloroplast (the [[proplastid]] too) but it is also synthesized in the [[cytosol]] and [[Mitochondrion|mitochondria]], probably because it has trouble crossing membranes to get to where it is needed.<ref name="Rolland-1992">{{cite journal | vauthors=Rolland N, Droux M, Douce R | title=Subcellular Distribution of O-Acetylserine(thiol)lyase in Cauliflower (Brassica oleracea L.) Inflorescence | journal=Plant Physiology | volume=98 | issue=3 | pages=927–35 | date=March 1992 | pmid=16668766 | pmc=1080289 | doi=10.1104/pp.98.3.927 }}</ref> The chloroplast is known to make the precursors to methionine but it is unclear whether the organelle carries out the last leg of the pathway or if it happens in the [[cytosol]].<ref name="Ravanel-1998">{{cite journal | vauthors=Ravanel S, Gakière B, Job D, Douce R | title=The specific features of methionine biosynthesis and metabolism in plants | journal=Proceedings of the National Academy of Sciences of the United States of America | volume=95 | issue=13 | pages=7805–12 | date=June 1998 | pmid=9636232 | pmc=22764 | doi=10.1073/pnas.95.13.7805 | bibcode=1998PNAS...95.7805R | doi-access=free }}</ref>