Plastids form a major proteinaceous compartment in plant and algal cells. For example, chloroplasts contain 2000 to 2500 proteins  and account for 75% to 80% of the total nitrogen in a leaf . Also, the dry weight of a chloroplast is 50% to 60% protein . It is well known that the concentrations of apparently all proteins in plant cells result from both synthesis and degradation of the individual proteins . Thus, plastid proteins, like those in other compartments of eukaryotic cells, are continually synthesized and subsequently degraded by a variety of proteases. Also, many plastid proteins are first synthesized as precursor molecules that are then processed to mature forms by proteases in the organelle (e.g., Ref. ).
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)