Ionic Effects on the Lateral Segregation of Chlorophyll-Proteins during Restacking of Thylakoid Membranes
The photosynthetic membrane of chloroplasts is differentiated into appressed and non-appressed (stroma exposed) areas. This structural differentiation is accompanied by a functional heterogeneity in the lateral plane of the membrane1. The photosystem 1 complex and the ATP synthase are mainly excluded from the appressed membrane regions and localized in the non-appressed regions. Most of the photosystem 2 complexes and its light-harvesting chlorophyll a/b complex (LHC-II) is located in the appressed regions. This lateral segregation of the thylakoid protein complexes has been postulated to involve repulsive electrostatic and attractive van der Waals forces at closely appressed membrane surfaces2. Under low salt conditions the thylakoid membranes destack and the membrane components are randomized along the membrane3. Readdition of cations reverses this process and restacking accompanied by lateral segregation of the complexes occurs.
KeywordsThylakoid Membrane Stroma Lamella Lateral Segregation Intact Thylakoid Control Thylakoid
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