PROSITE documentation PDOC00218
Phytochrome chromophore attachment site


Phytochrome [1,2,3] is a plant protein that acts as a regulatory photoreceptor and which mediates red-light effects on a wide variety of physiological and molecular responses. Phytochrome can undergo a reversible photochemical conversion between a biologically inactive red light-absorbing form and the active far-red light-absorbing form. Phytochrome is a dimer of identical 124 Kd subunits, each of which contains a covalently attached linear tetrapyrrole chromophore.

The chromophore is attached to a cysteine which is located in a highly conserved region that can be used as a signature pattern.

Synechocystis strain PCC 6803 hypothetical protein slr0473 contains a domain similar to that of plants phytochrome and seems to also bind a chromophore.

Expert(s) to contact by email:

Partis M.D.

Last update:

November 1997 / Pattern and text revised; profile.


Technical section

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

PHYTOCHROME_2, PS50046; Phytochrome chromophore attachment site domain profile  (MATRIX)

PHYTOCHROME_1, PS00245; Phytochrome chromophore attachment site signature  (PATTERN)


1AuthorsSilverthorne J. Tobin E.M.
SourceBioEssays 7:18-23(1987).

2AuthorsQuail P.H.
TitlePhytochrome: a light-activated molecular switch that regulates plant gene expression.
SourceAnnu. Rev. Genet. 25:389-409(1991).
PubMed ID1812812

3AuthorsQuail P.H.
TitleThe phytochromes: a biochemical mechanism of signaling in sight?
SourceBioEssays 19:571-579(1997).
PubMed ID9230690

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