Selective membrane protein internalization accompanies movement from the endoplasmic reticulum to the protein storage vacuole pathway in Arabidopsis.
In plant cells, certain membrane proteins move by unknown mechanisms directly from the endoplasmic reticulum (ER) to prevacuolar or vacuole-like organelles where membrane is internalized to form a dense, lattice-like structure. Here, we identify a sequence motif, PIEPPPHH, in the cytoplasmic tail of a membrane protein that directs the protein from the ER to vacuoles where it is internalized. A type II membrane protein in Arabidopsis thaliana, (At)SRC2 (for Soybean Gene Regulated by Cold-2), binds specifically to PIEPPPHH and moves from the ER to the same vacuoles where it is internalized. Not all proteins that move in this pathway are internalized because another Arabidopsis type II membrane protein, (At)VAP (for Vesicle-Associated Protein), localizes to the same organelles but remains exposed on the limiting membrane. The identification of (At)SRC2 and its preference for interaction with a targeting motif specific for the ER-to-vacuole pathway may provide tools for future dissection of mechanisms involved in this unique trafficking system.
Oufattole
Mohammed
M
Institute of Biological Chemistry, Washington State University, Pullman, Washington 99163, USA.
Park
Joon Ho
JH
Poxleitner
Marianne
M
Jiang
Liwen
L
Rogers
John C
JC
D020816:Amino Acid Motifs / Q000502:physiology; D017360:Arabidopsis / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D050683:R-SNARE Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism* / Q000648:ultrastructure
D029681:Arabidopsis Proteins; C000601165:At3g60600 protein, Arabidopsis; D008565:Membrane Proteins; D050683:R-SNARE Proteins; C510500:SRC2 protein, Arabidopsis