
TY  - JOUR
A1  - Takeuchi, TS 
A1  - Thornber, JP 
T1  - Heat-Induced Alterations in Thylakoid Membrane Protein Composition in Barley
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1994
VL  - 21
IS  - 6
SP  - 759
EP  - 770
KW  - 
UR  - https://doi.org/10.1071/PP9940759 
N2  - Biochemical and spectroscopic studies on the effects of high temperatures (45-47º C) over a 1 h period on the protein composition, fluorescence and photochemical activities of the barley thylakoid membrane were made. Photosystem II (PS II) activity decreased as expected, and photosystem I (PS I) activity also unexpectedly decreased. Our data support previous conclusions that the decrease in PS I activity is largely due to inactivation (or loss) of a component between the two photosystems. A two-dimensional electrophoretic system permitted first the separation of the thylakoid pigment-protein complexes of unstressed and stressed plants, followed by a determination of their subunit composition. The changes in the protein composition of each pigment-protein complex in response to elevated temperatures were monitored. Heat changed the quaternary structure of PS II and resulted in removal of the oxygen-evolving enhancer proteins from the thylakoid, but did essentially no damage to the PS I complex. The PS II core complex dissociated from a dimeric form to a monomeric one, and the major LHC II component (LHC IIb) changed from a trimeric to a monomeric form. The pigments that are lost from thylakoids during heat stress are mainly removed from the PS II pigment-proteins. 
ER  -

