The first is a light-dependent establishment of competence and the second involves transcriptional activation. The glycine decarboxylase complex has received the most study. All four nuclear encoded genes are light-activated. The increase is less with the L-protein due to its role in other mitochondrial multienzyme complexes. Phytochrome is the primary light receptor although a secondary signal from the mature chloroplasts is also essential.
Control is at the transcriptional level.
All four proteins are synthesized with N-terminal presequences that are responsible to mitochondrial targeting and are removed after import. Assembly of the complex is spontaneous in vitro and presumably in vivo . Transcriptional control of glycine decarboxylase. An predictable story with a twist. Protein level is controlled at the transcriptional level and the transcription of the gene closely follows that for the small subunit of Rubisco.