Light-harvesting complex polypeptides plants

The polypeptides of the light-harvesting complex are most easily resolved by polyacrylamide gel electrophoresis of thylakoid membranes solubilized with sodium or lithium dodecyl sulphate. This produces the green chlorophyll-protein band, CP II, which on staining for protein reveals up to four polypeptides of 24-27 kDa [2], each of which is believed to bind Chi a and Chi b. In most plants two polypeptides predominate, but other minor polypeptides may be resolved [2]. 

Harrison MA and Melis A. (1992). Organization and stability of polypeptides associated with the chlorophyll a-b light-harvesting complex of photosystem-II. Plant Cell Physiol. 33, 627-637. 

Fig. 4. (A) The side view of the LHC-II monomer in the membrane (lipid bilayer). The chlorophyll molecules are oriented nearly perpendicular to the membrane plane (the phytyl chains are omitted for clarity). Two lutein molecules form an internal X-shaped brace. (B) A sketch of the amino-acid sequence of the LHC-II polypeptide and a listing of the known Chl-residue ligation. White letters inside black circles indicate amino-acid ligands to the chlorophylls [also see legend on the right side of (B)]. Note that the model in (B) is rotated 90° with respect to that in (A) about an axis normal to the membrane. Figure source (A) Kuhibrandt, Wang and Fujiyoshi (1994) Atomic model of plant light-harvesting complex by electron crystallography. Nature 367 618 and 620.

MM Stayton, P Brosio and P Dunsmuir (1987) Characterization of a full length petunia cDNA encoding a polypeptide of the light-harvesting complex associated with photosystem I. Plant Mol Biol 10 127-137... 

Photosystem II is the multi-enzymatic chlorophyll-protein complex (water-plastoquinone oxido-reductase) located in the thylakoid membrane of algae, cyanobacteria and higher plants. It is an integral part of the electron transport chain that catalyses primary charge separation. This protein complex consists of over 25 polypeptides, which make up a light-harvesting chlorophyll protein... 

The light-harvesting chlorophyll complex (LHC II) of green plant chloroplasts accounts for about half the chlorophyll and a third of the protein of the thylakoid membrane (1,2). For each polypeptide of between 24 and 27 kDa, the complex contains 4 chlorophyll a molecules, 3 chlorophyll b molecules and 1-2 xanthophyll molecules. Each polypeptide is encoded by one of a family of nuclear genes. 

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