Protein Import Apparatus of Chloroplast

摘要

The chloroplast has its origin through endosymbiosis involving a cyanobateria. During the process of evolution it compromised with its genetic autonomy resulting in lateral transfer of host majority of chloroplast genome to the nucleus of the cell inwhich it is harboured. Although the chloroplast contain around 3000 proteins, its genome codes only for about 100 proteins. Thus it is obvious that a majority of the chloroplast proteins are encoded by nucleus and post-translationally imported into the chloroplast. This unidirectional movement of the precursor proteins occurs in an energy-dependent manner through a hetero-oligomeric machinery, i.e. translocon at outer envelope of chloroplast (TOC) and translocon at inner envelope of chloroplast (TIC) complex present on the outer and inner envelope of the chloroplast respectively. Proper development and functioning of chloroplast is dependent on abundant expression of the various components of the protein import apparatus.