Transport of ricin and 2S albumin precursors to the storage vacuoles of Ricinus communis endosperm involves the Golgi and VSR-like receptors.
We have studied the transport of proricin and pro2S albumin to the protein storage vacuoles of developing castor bean (Ricinus communis L.) endosperm. Immunoelectron microscopy and cell fractionation reveal that both proteins travel through the Golgi apparatus and co-localize throughout their route to the storage vacuole. En route to the PSV, the proteins co-localize in large (>200 nm) vesicles, which are likely to represent developing storage vacuoles. We further show that the sequence-specific vacuolar sorting signals of both proricin and pro2SA bind in vitro to proteins that have high sequence similarity to members of the VSR/AtELP/BP-80 vacuolar sorting receptor family, generally associated with clathrin-mediated traffic to the lytic vacuole. The implications of these findings in relation to the current model for protein sorting to storage vacuoles are discussed.
Jolliffe
Nicholas A
NA
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
Brown
Joanna C
JC
Neumann
Ulla
U
Vicré
Maïte
M
Bachi
Angela
A
Hawes
Chris
C
Ceriotti
Aldo
A
Roberts
Lynne M
LM
Frigerio
Lorenzo
L
D055516:2S Albumins, Plant; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D002367:Ricinus communis / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D012276:Ricin / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism* / Q000648:ultrastructure
D055516:2S Albumins, Plant; C541551:2S storage protein, Ricinus communis; D052179:Antigens, Plant; D010446:Peptide Fragments; D010940:Plant Proteins; D012276:Ricin