COG complexes form spatial landmarks for distinct SNARE complexes

Abstract

Vesicular tethers and SNAREs are two key protein components of the intracellular membrane trafficking machinery. The COG (conserved oligomeric Golgi) complex has been implicated in the tethering of retrograde intra-Golgi vesicles. Here, using yeast two hybrid and co-immunoprecipitation approaches, we show that three COG subunits, namely COG4, 6, and 8, are capable of interacting with defined Golgi SNAREs, namely STX5, STX6, STX16, GS27, and SNAP29. Comparative analysis of COG8-STX16 and COG4-STX5 interactions by a COG-based mitochondrial re-localization assay reveals that the COG8 and COG4 proteins initiate the formation of two different tethering platforms that can facilitate the redirection of two populations of Golgi transport intermediates to the mitochondrial vicinity. Our results uncover a role for COG subcomplexes in defining the specificity of vesicular sorting within the Golgi.

The Calcineurin Variant CnAβ1 Controls Mouse Embryonic Stem Cell Differentiation by Directing mTORC2 Membrane Localization and Activation

“…This localization depends on the interaction of CnAβ1 with Cog8. Cog8 is an important player in the stabilization of the Cog and SNARE complexes required for the tethering and transport of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 vesicles to the Golgi, and in the regulation of the proper compartmentalization of Golgi proteins (Laufman et al, 2013;Willett et al, 2013). The localization at the Golgi apparatus is specific of CnAβ1 and suggests that this calcineurin isoform plays a different role from that of CnAβ2, which is distributed throughout the cytoplasm of the cell.…”

“…In addition to known CnA interacting proteins like CnB (Felkin et al, 2011), we identified the interaction between CnAβ1 and Cog8, a protein enriched mainly in the external Golgi as well as other intracellular membranes that is involved in the interaction with the Cog and SNARE complexes (Laufman et al, 2013;Willett et al, 2013;Willett et al, 2014) (Table S4). To validate this interaction, we transfected cells with GFP-CnAβ1 chimeras and carried out immunoprecipitation and colocalization experiments.…”

Multipronged interaction of the COG complex with intracellular membranes

“…Our previous work has shown that one of the functions of the COG complex is to serve as a landmark for two SNARE complexes, the cis-Golgi localized STX5 containing SNARE complex, and the trans-Golgi localized STX16 containing SNARE complex. 34 In order for the COG complex to organize these SNARE complexes, it is critical that they interact in the correct Golgi compartment. We believe that it is through the COGs multiple interaction profiles with membrane-bound partners (i.e., Rabs, SNAREs, coiled-coil tethers such as p115) that the compartment specificity of the COG complex is achieved.…”

“…Plasmids expressing FRB and FKBP12 fragments were obtained from Dr. Gambhir (Stanford University).To generate hCOG4-GFP-FRB and hCOG8-GFP-FRB constructs NdeI/KpnI fragments of siRNA-resistant hCOG4 and hCOG8 34 were sub-cloned into similarly digested c-Luc-FRB plasmid.…”

Congenital disorders of glycosylation: a concise chart of glycocalyx dysfunction

“…Alterations in lobe A lead to accumulation of late glycosylation enzymes in COG complex vesicles, thereby preventing interaction with their substrate. Lobe B rather mediates vesicular sorting of trans-Golgi enzymes through functional interactions with the tethering and fusion machinery of trans-Golgi cisternae [67,68]. Accordingly, glycosyltransferases from early Golgi cisternae, such as the 1-2 GlcNAc-transferase MGAT1, are more affected by a defect in lobe A [66].…”