At least two Toc34 protein import receptors with different specificities are also present in spinach chloroplasts.
The receptor components of the chloroplast protein import machinery, Toc34 and Toc159, are both encoded by small gene families in Arabidopsis thaliana. Recent results suggest that each member of these families preferentially interacts with different groups of precursor proteins. Here we address the question, whether multiple homologous Toc receptors are unique to Arabidopsis or whether they are a general phenomenon in plants. Indeed, in spinach we could identify at least two Toc34 proteins with different substrate specificities as demonstrated by competition and antibody inhibition experiments. In addition, an analysis of the available genomic data revealed the presence of at least two Toc34 homologs in six other plant species.
Voigt
Andrea
A
Institut für Pflanzenphysiologie, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 10, D-06120 Halle, Germany.
Jakob
Mario
M
Klösgen
Ralf Bernd
RB
Gutensohn
Michael
M
D017360:Arabidopsis / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D018724:Spinacia oleracea / Q000378:metabolism*; D013379:Substrate Specificity
D008565:Membrane Proteins; D010940:Plant Proteins; C112475:Toc34 protein, plant