The sequences of the nuclear genes of the 33 kDa (OEE1) and the 16 kDa (OEE3) polypeptides of the oxygen evolving complex of Chlamydomonas reinhardtii have been established. Comparison between the OEE1 protein sequences of C. reinhardtii and higher plants and cyanobacteria reveals 67 and 47% homology. In contrast, C. reinhardtii and higher plants have only 28 % overall homology for OEE3 which is mostly limited to the central portion of the protein. The transit peptides of the C. reinhardtii proteins consist of 52 (OEE1) and, most likely, 51 (OEE1) amino acids. They have a basic amino terminal region and, at least in the case of OEE 1, a hydrophobic segment at their carboxy terminal end typical ofthylakoid lumen proteins. Comparison of the genomic and cDNA clones indicates that the OEE1 and OEE3 genes contain five and four introns, respectively, some of which are located within the coding sequences of the transit peptides.
* The nucleotide sequence data reported will appear in the EMBL, the accession number X13826 (OEE1) and X13832 (OEE3).
evolving particles are complex assemblies containing chlorophylls a and b, carotenoids, quinones, lipids, iron, a catalytic manganese cluster and an array of at least nine polypeptides [1,2]. PSII proteins can be grouped into two distinct classes. The first includes the core PSII proteins which are integral membrane proteins encoded by the chloroplast genome. The second includes the three extrinsic proteins of the oxygenevolving complex called oxygen-evolving enhan-GenBank and DDBJ Nucleotide Sequence Databases under