A green fluorescent protein fused to rice prolamin forms protein body-like structures in transgenic rice.
Prolamins, a group of rice (Oryza sativa) seed storage proteins, are synthesized on the rough endoplasmic reticulum (ER) and deposited in ER-derived type I protein bodies (PB-Is) in rice endosperm cells. The accumulation mechanism of prolamins, which do not possess the well-known ER retention signal, remains unclear. In order to elucidate whether the accumulation of prolamin in the ER requires seed-specific factors, the subcellular localization of the constitutively expressed green fluorescent protein fused to prolamin (prolamin-GFP) was examined in seeds, leaves, and roots of transgenic rice plants. The prolamin-GFP fusion proteins accumulated not only in the seeds but also in the leaves and roots. Microscopic observation of GFP fluorescence and immunocytochemical analysis revealed that prolamin-GFP fusion proteins specifically accumulated in PB-Is in the endosperm, whereas they were deposited in the electron-dense structures in the leaves and roots. The ER chaperone BiP was detected in the structures in the leaves and roots. The results show that the aggregation of prolamin-GFP fusion proteins does not depend on the tissues, suggesting that the prolamin-GFP fusion proteins accumulate in the ER by forming into aggregates. The findings bear out the importance of the assembly of prolamin molecules and the interaction of prolamin with BiP in the formation of ER-derived PBs.
Saito
Yuhi
Y
Laboratory of Genetic Engineering, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo, Kyoto 606-8522, Japan.
Kishida
Koichi
K
Takata
Kenji
K
Takahashi
Hideyuki
H
Shimada
Takeaki
T
Tanaka
Kunisuke
K
Morita
Shigeto
S
Satoh
Shigeru
S
Masumura
Takehiro
T
D022082:Cellular Structures / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D008623:Mercaptoethanol / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D018832:Molecular Chaperones / Q000378:metabolism; D012275:Oryza / Q000166:cytology / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D055315:Prolamins / Q000235:genetics / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D012639:Seeds / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D012995:Solubility / Q000187:drug effects; D013213:Starch / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
D018832:Molecular Chaperones; D010940:Plant Proteins; D055315:Prolamins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D008623:Mercaptoethanol; D013213:Starch