Membrane tethering in intracellular transport

Studies of various membrane trafficking steps over the past year indicate t hat membranes are tethered together prior to the interaction of v-SNAREs an d t-SNAREs across the membrane junction, The tethering proteins identified to date are quite large, being either fibrous proteins or multimeric protei n complexes, The tethering factors employed at different steps are evolutio narily unrelated, yet their function seems to be closely tied to the more h ighly conserved Rab GTPases, Tethering factors may collaborate with Rabs an d SNAREs to generate targeting specificity in the secretory pathway.