Plant-specific insertions in the soybean aspartic proteinases, soyAP1 and soyAP2, perform different functions of vacuolar targeting.
Most aspartic proteinases (APs) of plant origin are characterized by the presence of plant-specific insertion (PSI) in their primary structure. PSI has been reported to function as signals for both transport of AP molecules from the endoplasmic reticulum (ER) and for their targeting to the vacuole. To determine the functions of the PSIs in soyAP1 and soyAP2 identified in our previous study, we examined their subcellular localization by transient expression of a green fluorescent protein (GFP) fusion protein in the protoplasts of Arabidopsis suspension-cultured cells. Both soyAP1-GFP and soyAP2-GFP were targeted to the vacuole. To confirm the role of the PSI, we prepared PSI-deleted soyAP1 and soyAP2, and investigated their vacuolar targeting by the same method. While the former deletion mutant was always transported to the vacuole, the latter sometimes remained in the ER and was only sometimes transported to the vacuole. These observations indicated that, in the case of soyAP1, the PSI is not involved in vacuolar targeting, also suggesting that the function of the PSI differs depending on its origin.
Terauchi
Kaede
K
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Asakura
Tomiko
T
Ueda
Haruko
H
Tamura
Tomoko
T
Tamura
Kentaro
K
Matsumoto
Ichiro
I
Misaka
Takumi
T
Hara-Nishimura
Ikuko
I
Abe
Keiko
K
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000648:ultrastructure; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000032:analysis; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000648:ultrastructure; D021382:Protein Sorting Signals; D021381:Protein Transport / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis; D016415:Sequence Alignment; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics; D014617:Vacuoles / Q000201:enzymology* / Q000648:ultrastructure
D010940:Plant Proteins; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D016282:Aspartic Acid Endopeptidases