{PDOC00217} {PS00244; REACTION_CENTER} {BEGIN} ***************************************************** * 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. -Consensus pattern: [NQH]-x(4)-P-x-H-x(2)-[SAG]-x(11)-[SAGC]-x-H-[SAG](2) [The first H is a magnesium ligand] [The second H is a iron ligand] -Sequences known to belong to this class detected by the pattern: ALL, except for broad bean psbA which has Gln instead of the second His. -Other sequence(s) detected in Swiss-Prot: NONE. -Expert(s) to contact by email: Edelman M.; lpedel@weizmann.weizmann.ac.il Hirschberg J.; hirschu@hujivms.huji.ac.il -Last update: December 2001 / Pattern and text revised. [ 1] Michel H., Deisenhofer J. Biochemistry 27:1-7(1988). [ 2] Barber J. Trends Biochem. Sci. 12:321-326(1987). -------------------------------------------------------------------------------- PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html -------------------------------------------------------------------------------- {END}