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XVI.B.1.b. D2
Sequences of D2
Sequence Similarity Search for D2
XVI.B.1.b. D2
The D1 and D2 proteins are believed to carry all cofactors needed for the primary photoreactions except the quinones (for a general review see Akerlund, 1993). In analogy with the reaction center of the purple bacteria, it has been proposed that the D1 and D2 proteins form an interwined heterodimer complex, with P680 being located between the D1 and D2 subunits. the donor Z-tyrosine, the acceptor pheophytin, as well as the QB site are assigned to the D1 protein. This complex is called the active branch. The D2 protein carries the QA site as well as a donor D ( a tyrosine) and a pheophytin molecule. The components carried by D2 are not directly involved in the primary charge separation and constitute the dead branch of the heterodimer.
The D1 and D2 proteins are hydrophobic membrane proteins. It has been proposed that both proteins exhibit five membrane-spanning helices with the N-terminus on the stromal side and the D- and Z-tyrosine residues on the luminal side of the membrane.
Amino acids believed ot be involved in plastoquinone binding and herbicide binding and\or resistance are believed to be located at or close to the stromal side.
A query for D2 addressed to the various protein databases listed in the Biology Workbench, yielded 43 records which are depicted under Sequenced D2. These sequences can be used for Sequence Similarity Searches or other manipulations using one of several routines described in the Biology Workbench or elsewhere (see AntheproW which can be downloaded via anonymous ftp from: ibcp.fr; pub/Antheprot/Windows/anthe 3_1 directory). For example a Blast Sequence Similarity Search of maize D2 addressed to the Biology Workbench (SwissProt database) is depicted below.
Sequences of D2
Click on Sequences to view the sequences of D2 retrieved from various protein sequence databases by the Biology Workbench.
Sequence Similarity Search for D2
Click on Sequence Similarity Search to view the Blast sequence similarity search results of maize D2 as retrieved by the Biology workbench (SwissProt database).
References
- Akerlund, H-E (1993). Function and organization of photosystem II. In: Pigment-Protein Complexes In Plastids: Synthesis and Assembly . C. Sundqvist and M. Ryberg, (eds.), p 419-446, Academic Press, New York.