Abstract
Plastids perform a number of essential biochemical functions. Since most of the proteins are encoded in nucleus, they are synthesized as precursor proteins and are imported into plastids by preprotein translocases. The translocon at the outer membrane of chloroplasts (Toc complex) and the translocon inner membrane of chloroplasts (Tic complex) act co-operatively during the import process. Although putative components of the import apparatus have been identified biochemically using isolated pea (Pisum sativum) chloroplasts, their role in import remains to be proven in vivo. With the completion of the Arabidopsis genome sequencing project, it is now possible to identify putative homologs of the import components in this species. Arabidopsis mutants lacking one of the Tic component has been isolated. The content of chloroplast pigments were reduced proportionally. Additionally, morphological and biochemical data demonstrate that the effects on leaf development by the translocon mutation.
