Different requirements for NSF, SNAP, and Rab proteins in apical and basolateral transport in MDCK cells

Membrane transport of epithelial Madin-Darby canine kidney (MDCK) cells was inhibited by anti-N-ethylmaleimide-sensitive factor (NSF) in a permeabilized cell system, but was stimulated by alpha-soluble NSF attachment proteins. However, transport of cells from the trans-Golgi network to the apical cell surface was not affected by these proteins. Apical transport was also not affected by Rab-GDI and tetanus and botulinum neurotoxins which inhibit basolateral transport, suggesting that the Rab-NSF-SNAP-SNARE machinery only operates in basolateral transport.