STRUCTURAL RELATIONSHIPS OF THE PHOTOSYSTEM I AND PHOTOSYSTEM II CHLOROPHYLL a/b AND a/c LIGHT-HARVESTING APOPROTEINS OF PLANTS AND ALGAE |
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Authors: | F. Gerald,Plumley ,Tracey A.,Martinson ,David L.,Herrin ,Masahiko,Ikeuchi&dagger Gregory W.,Schmidt&dagger |
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Affiliation: | Institute of Marine Science, University of Alaska, Fairbanks, AK 99775, USA;Botany Department, University of Georgia, Athens, GA 30602, USA |
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Abstract: | Polyclonal antibodies against four different apoproteins of either the chlorophyll (Chl) a/b light-harvesting antenna of photosystem I or II, or a chlorophyll-protein complex homologous to CP26 from Chlamydomonas reinhardtii, crossreact with11–13 thylakoid proteins of Chlamydomonas, Euglena gracilis and higher plants. The number of antigenically-related proteins correlates with the quantity of light-harvesting chlorophyll-protein complex (LHC) gene types that have been sequenced in higher plants. The antibodies also react specifically with Chi a/c-binding proteins of three diatoms and Coccolithophora sp. as determined by immunoblot and Ouchterlony assays. Four to six crossreacting proteins are observed in each chromophyte species and a functional role for some can be deduced by antibody reactivity. It appears that despite major differences in the structures of their pigment ligands, at least some domains of Chl-binding LHC apoproteins have been conserved during their evolution, possibly functioning in protein: protein, as opposed to pigment: protein, interactions in photosynthetic membranes. |
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