| Popis: |
Most of the chlorophyll in eukaryotic organisms is bound to intrinsic light-harvesting complexes. Although these complexes have apoproteins of widely differing Mr (17–30kDa) and bind almost the entire range of photosynthetic pigments, they are evolutionarily related [1]. In the model proposed for Pea LHCII [2] the chlorophylls are bound to the transmembrane helices and sequence alignments suggest putative chlorophyll-binding residues are conserved among even distantly related LHCs [1,3–6]. Another common feature is that LHC proteins are encoded by multigene nuclear families, although the roles of the different members are not clear. In two groups of algae, Euglenoids [7] and Dinoflagellates [8], multiple LHC genes have become fused and encode large polyproteins, which are cleaved after transfer to the chloroplast. We report here approximately 3kb of the sequence of an LHC gene from Amphidinium including the 5’ end. The pattern of introns supports a differential splicing explanation for the dramatic size variation (6kb reducing to 3kb) of LHC mRNA when algae are grown at low or intermediate light intensities [9]. |
