The life of ribulose 1,5-bisphosphate carboxylase/oxygenase--posttranslational facts and mysteries.

The life of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), from gene to protein to irreplaceable component of photosynthetic CO2 assimilation, has successfully served as a model for a number of essential cellular processes centered on protein chemistry and amino acid modifications. Once translated, the two subunits of Rubisco undergo a myriad of co- and posttranslational modifications accompanied by constant interactions with structurally modifying enzymes. Even after final assembly, the essential role played by Rubisco in photosynthetic CO2 assimilation is dependent on continuous conformation modifications by Rubisco activase. Rubisco is also continuously assaulted by various environmental factors, resulting in its turnover and degradation by processes that appear to be enhanced during plant senescence.