Modifications at the A-domain of the chloroplast import receptor Toc159.
Two families of GTPases, the Toc34 and Toc159 GTPase families, take on the task of preprotein recognition at the translocon at the outer membrane of chloroplasts (TOC translocon). The major Toc159 family members have highly acidic N-terminal domains (A-domains) that are non-essential and so far have escaped functional characterization. But recently, interest in the role of the A-domain has strongly increased. The new data of three independent studies provide evidence that the Toc159 A-domain I) participates in preprotein selectivity, II) has typical features of intrinsically unfolded proteins and III) is highly phosphorylated and possibly released from the rest of the protein by a proteolytic event. This hints to a complex regulation of A-domain function that is important for the maintenance of the preprotein selectivity at the TOC translocons.
Institut für Biochemie und Biotechnologie, Abteilung für Pflanzenbiochemie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany.
Birgit
B
Agne
Felix
F
Kessler
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D021381:Protein Transport
D029681:Arabidopsis Proteins; D008565:Membrane Proteins; C403444:TOC159 protein, Arabidopsis; D020558:GTP Phosphohydrolases