title: Are all multisubunit tethering complexes bona fide tethers?
abstract: Since the late 1990s, a number of multisubunit tethering complexes (MTCs) have been described that function in membrane trafficking events: TRAPP I, TRAPP II, TRAPP III, COG, HOPS, CORVET, Dsl1, GARP and exocyst. On the basis of structural and sequence similarities, they have been categorized as complexes associated with tethering containing helical rods (CATCHR) (Dsl1, COG, GARP and exocyst) or non-CATCHR (TRAPP I, II and III, HOPS and CORVET) complexes (Yu IM, Hughson FM. Tethering factors as organizers of intracellular vesicular traffic. Annu Rev Cell Dev Biol 2010;26:137-156). Both acronyms (CATCHR and MTC) imply these complexes tether opposing membranes to facilitate fusion. The main question we will address is: have these complexes been formally demonstrated to function as tethers? If the answer is no, then is it premature or even correct to refer to them as tethers? In this commentary, we will argue that the vast majority of MTCs have not been demonstrated to act as a tether. We propose that a distinction between the terms tether and tethering factor be considered to address this issue.
authors.affiliation: Department of Biology, Concordia University, Montreal, Quebec, Canada.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Brunet
authors.forename: Michael
authors.initials: M
authors.lastname: Sacher
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D055503:Protein Multimerization; D021381:Protein Transport; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: D033921:Vesicular Transport Proteins
keywords: CATCHR; COG; CORVET; Dsl1; GARP; HOPS; TRAPP; exocyst; tether