PT  - JOURNAL ARTICLE
AU  - Larkin, Robert M.
AU  - Alonso, Jose M.
AU  - Ecker, Joseph R.
AU  - Chory, Joanne
TI  - GUN4, a Regulator of Chlorophyll Synthesis and Intracellular Signaling
AID  - 10.1126/science.1079978
DP  - 2003 Feb 07
TA  - Science
PG  - 902--906
VI  - 299
IP  - 5608
4099  - http://science.sciencemag.org/content/299/5608/902.short
4100  - http://science.sciencemag.org/content/299/5608/902.full
SO  - Science2003 Feb 07; 299
AB  - Nuclear genes control plastid differentiation in response to developmental signals, environmental signals, and retrograde signals from plastids themselves. In return, plastids emit signals that are essential for proper expression of many nuclear photosynthetic genes. Accumulation of magnesium-protoporphyrin IX (Mg-Proto), an intermediate in chlorophyll biosynthesis, is a plastid signal that represses nuclear transcription through a signaling pathway that, inArabidopsis, requires the GUN4 gene. GUN4 binds the product and substrate of Mg- chelatase, an enzyme that produces Mg-Proto, and activates Mg-chelatase. Thus, GUN4 participates in plastid-to-nucleus signaling by regulating Mg-Proto synthesis or trafficking.