PROSITE documentation PDOC00786 [for PROSITE entry PS01026]
Photosystem I psaG and psaK proteins signature


Photosystem I (PSI) [1] is an integral membrane protein complex that uses light energy to mediate electron transfer from plastocyanin to ferredoxin. It is found in the chloroplasts of plants and cyanobacteria. PSI is composed of at least 14 different subunits, two of which - PSI-G (gene psaG) and PSI-K (gene psaK) - are small hydrophobic proteins of about 7 to 9 Kd and evolutionary related [2]. Both seem to contain two transmembrane regions. Cyanobacteria seem to encode only for PSI-K.

As a signature pattern, we selected the best conserved region which seems to correspond to the second transmembrane region.

Last update:

December 2004 / Pattern and text revised.


Technical section

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

PHOTOSYSTEM_I_PSAGK, PS01026; Photosystem I psaG and psaK proteins signature  (PATTERN)


1AuthorsGolbeck J.H.
TitleStructure, function and organization of the Photosystem I reaction center complex.
SourceBiochim. Biophys. Acta 895:167-204(1987).
PubMed ID3333014

2AuthorsKjaerulff S. Andersen B. Nielsen V.S. Moller B.L. Okkels J.S.
TitleThe PSI-K subunit of photosystem I from barley (Hordeum vulgare L.). Evidence for a gene duplication of an ancestral PSI-G/K gene.
SourceJ. Biol. Chem. 268:18912-18916(1993).
PubMed ID8360180

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 prosite_license.html.


View entry in original PROSITE document format
View entry in raw text format (no links)