Basolateral Protein Transport in Streptolysin O-Permeabilized MDCK Cells

• Published in: The Journal of cell biology 1994-06, Vol.125 (5), p.1025-1035
• Main Authors: Pimplikar, Sanjay W., Ikonen, Elina, Simons, Kai
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antibodies; Bacterial Proteins; Biological and medical sciences; Biological Transport; Cell Line; Cell lines; Cell Membrane Permeability; Cell membranes; Cell physiology; Cell Polarity; Cells; Cellular biology; Cytoplasm - metabolism; Cytosol; Dogs; Epithelial cells; Fundamental and applied biological sciences. Psychology; Gels; Glycoproteins; Golgi Apparatus - metabolism; In Vitro Techniques; Intracellular Membranes - metabolism; Kidney cells; Membrane and intracellular transports; Membrane Glycoproteins - metabolism; Membrane proteins; Molecular and cellular biology; Molecular Sequence Data; Peptides - chemistry; Proteins; Streptolysins - pharmacology; Viral Envelope Proteins - chemistry; Viral Envelope Proteins - metabolism
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.125.5.1025

We have reconstituted polarized protein transport in streptolysin O-permeabilized MDCK cells from the TGN to the basolateral surface and to the apical surface. These transport steps are dependent on temperature, energy and exogenously supplied cytosol. Using this in vitro system we show that a whole tail peptide (WT peptide) corresponding to the cytoplasmic tail of a basolaterally sorted protein, the vesicular stomatitis virus glycoprotein (VSV G) inhibits the TGN to basolateral transport but does not affect any other transport step. Inhibition of VSV G transport to basolateral surface by WT peptide did not result in missorting of the protein to the apical surface. Mutation of the single tyrosine residue in the WT peptide reduced its inhibitory potency four- to fivefold. These results suggest that the VSV G tail physically interacts with a component of the sorting machinery. Using a cross-linking approach, we have identified proteins that associate with the cytoplasmic tail domain of VSV G. One of these polypeptides, Tin-2 (Tail interacting protein-2), associates with VSV G in the TGN, the site of protein sorting, but not in the ER nor at the cell surface. Tin-2 does not associate with apically targeted hemagglutinin. WT peptide that inhibited the basolateral transport of VSV G also inhibited the association of Tin-2 with VSV G. Together, these properties make Tin-2 a candidate basolateral sorter. The results demonstrate the usefulness of the SLO-permeabilized cell system in dissecting the sorting machinery.