A Toc75-like protein import channel is abundant in chloroplasts.
Chloroplasts import post-translationally most of their constituent polypeptides via two distinct translocon units located in the outer and inner envelope. The protein import channel of the translocon of the outer envelope of chloroplasts, Toc75, is the most abundant protein in that membrane. We identify a novel Toc75 homologous protein, atToc75-V, a prominent protein that is clearly localized in the chloroplastic outer envelope. Phylogenetic analysis indicates that Toc75-V is more closely related to its prokaryotic ancestors than to Toc75 from plants. The presence of a second translocation channel suggests that alternative, previously unrecognized import routes into chloroplasts might exist.
Eckart
Kerstin
K
Department für Biologie I, Menzinger Strasse 67, Ludwig-Maximilians-Universität, D-80638 München, Germany.
Eichacker
Lutz
L
Sohrt
Karen
K
Schleiff
Enrico
E
Heins
Lisa
L
Soll
Jürgen
J
D000595:Amino Acid Sequence; D002736:Chloroplasts / Q000737:chemistry*; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D018532:Pisum sativum / Q000737:chemistry*; D010940:Plant Proteins; D011498:Protein Precursors / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D008565:Membrane Proteins; C103933:OEP75 protein precursor, plant; D010940:Plant Proteins; D011498:Protein Precursors