The barley lectin carboxyl-terminal propeptide is a vacuolar protein sorting determinant in plants.
We have previously shown that the 15-amino acid carboxyl-terminal propeptide of probarley lectin is necessary for the proper sorting of this protein to the plant vacuole. A mutant form of the protein lacking the carboxyl-terminal propeptide is secreted. To test whether the carboxyl-terminal propeptide is the vacuole sorting determinant of probarley lectin, we examined in transgenic tobacco the processing and sorting of a series of fusion proteins containing the secreted protein, cucumber chitinase, and regions of probarley lectin. Pulse-labeling experiments demonstrated that the fusion proteins were properly translocated through the tobacco secretory system and that cucumber chitinase and cucumber chitinase fusion proteins lacking the carboxyl-terminal propeptide were secreted. The cucumber chitinase fusion protein containing the carboxyl-terminal propeptide was properly processed and sorted to the vacuole in transgenic tobacco as confirmed by organelle fractionation and electron microscopy immunocytochemistry. Therefore, the barley lectin carboxyl-terminal propeptide is both necessary and sufficient for protein sorting to the plant vacuole.
Bednarek
S Y
SY
Department of Energy Plant Research Laboratory, Michigan State University, East Lansing 48824-1312.
Raikhel
N V
NV
D000595:Amino Acid Sequence; D006031:Glycosylation; D001467:Hordeum / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D037102:Lectins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D037121:Plant Lectins; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
D037102:Lectins; D037121:Plant Lectins; D010940:Plant Proteins; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins