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PROSITE documentation PDOC00217 [for PROSITE entry PS00244]

Photosynthetic reaction center proteins signature


In the photosynthetic reaction center of purple bacteria, two homologous integral membrane proteins, L(ight) and M(edium), are known to be essential to the light-mediated water-splitting process. In the photosystem II of eukaryotic chloroplasts two related proteins are involved: the D1 (psbA) and D2 proteins (psbD). These four types of protein probably evolved from a common ancestor [see 1,2 for recent reviews].

We developed a signature pattern which include two conserved histidine residues. In L and M chains, the first histidine is a ligand of the magnesium ion of the special pair bacteriochlorophyll, the second is a ligand of a ferrous non-heme iron atom. In photosystem II these two histidines are thought to play a similar role.

Expert(s) to contact by email:

Edelman M.
Hirschberg J.

Last update:

December 2001 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

REACTION_CENTER, PS00244; Photosynthetic reaction center proteins signature  (PATTERN)


1AuthorsMichel H. Deisenhofer J.
SourceBiochemistry 27:1-7(1988).

2AuthorsBarber J.
SourceTrends Biochem. Sci. 12:321-326(1987).

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