PROSITE documentation PDOC00217
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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