In recent years there has been extensive experimental evidence indicating that the nuclear expression of certain genes , in particular those that encode chloroplast proteins is subject to regulation by signals of retrograde plastid origin . This can be done both at the level of transcription and translation of mRNA . Certain plastid origin signals could be identified - these include metabolic precursor of chlorophyll plastochinonu redox state , thioredoxin and glutathione and phosphoenolpyruvate translocator located in the chloroplast inner envelope membrane .

Controlled degradation of the proteins is involved in the regulation of many important cellular processes , including cell cycle , differentiation , management and distribution of protein , and programmed cell death. For several years, it is known that the degradation of specific proteins is also a very important part of the mechanisms governing the biogenesis of chloroplasts and their adaptations to changing environmental conditions and that the protease responsible for the digestion of proteins are localized in the chloroplast chloroplasts themselves .