The COG complex and CUX1 and GOLGA5 dimers contribute to intra-Golgi vesicle tethering

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Homo sapiens
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Dimeric medial Golgins CUX1 (also known as CASP) and GOLGA5 (also known as Golgin-84) act in conjunction with the COG complex to tether retrograde vesicles moving within the Golgi stacks (Bascom et al, 1999; Gillingham et al, 2002; Malsam et al, 2005; Sohda et al, 2007; Sohda et al, 2010; reviewedin Szul and Sztul, 2011). Intra-Golgi vesicles are COPI-dependent, but distinct from anterograde ERGIC-to-Golgi COPI vesicles by virtue of their cargo (generally returning Golgi and ER-resident enzymes to their appropriate location in the secretory pathway, and notably lacking p24 family members; other intra Golgi cargo includes toxins such as Shiga) and the SNARE complexes they interact with (Orci et al, 1997; Lanoix et al, 2001; Malsam et al, 2005). The yeast homologue of GOLGA5, COY1, shows a genetic interaction with yeast SNARE GOS1 (human GOSR1), suggesting the intra-Golgi vesicles may rely on a GOSR1:STX5:BET1L and YKT6 SNARE complex, though the identity of the t-SNARE complex remains to be substantiated (Gillingham et al, 2002; Sohda et al, 2010). Removal of the COPI-coat is required prior to CUX1- and GOLGA5-mediated vesicle tethering (Malsam et al, 2005). Intra-Golgi transport also depends on medial RAB protein RAB33b (Jiang et al, 2005; Valsdottir et al, 2001; Pusapati et al, 2012; Starr et al, 2010). Disruption of RAB33b abolishes retrograde traffic of Shiga toxin from the trans- to cis-Golgi, and abolishes the RAB6-dependent relocalization of Golgi resident enzymes. This suggests that RAB6 and RAB33b may form sequentially acting RAB cascade that mediates intra-Golgi traffic (Starr et al, 2010; Pusapati et al, 2012). RAB33b has also been shown to interact with the RAB6 GEF RIC1:RGP1, although the significance of this interaction is unclear. In addition, RAB33b interacts by co-immunoprecipitation with endosomal proteins RABEP1 (also known as Rabaptin-5), RABGEF1 (Rabex5) and KIF20A (Rabkinesin 6); the relevance of these interactions is likewise unknown (Valsdottir et al, 2001).

Literature References
PubMed ID Title Journal Year
8636227 A v-SNARE implicated in intra-Golgi transport

Nagahama, M, Orci, L, Ravazzola, M, Amherdt, M, Lacomis, L, Tempst, P, Rothman, JE, Söllner, TH

J. Cell Biol. 1996
20874812 Interaction of Golgin-84 with the COG complex mediates the intra-Golgi retrograde transport

Sohda, M, Misumi, Y, Yamamoto, A, Nakamura, N, Ogata, S, Sakisaka, S, Hirose, S, Ikehara, Y, Oda, K

Traffic 2010
11748249 Sorting of Golgi resident proteins into different subpopulations of COPI vesicles: a role for ArfGAP1

Lanoix, J, Ouwendijk, J, Stark, A, Szafer, E, Cassel, D, Dejgaard, K, Weiss, M, Nilsson, T

J. Cell Biol. 2001
9244307 Bidirectional transport by distinct populations of COPI-coated vesicles

Orci, L, Stamnes, M, Ravazzola, M, Amherdt, M, Perrelet, A, Söllner, TH, Rothman, JE

Cell 1997
17274799 The interaction of two tethering factors, p115 and COG complex, is required for Golgi integrity

Sohda, M, Misumi, Y, Yoshimura, S, Nakamura, N, Fusano, T, Ogata, S, Sakisaka, S, Ikehara, Y

Traffic 2007
12429822 CASP, the alternatively spliced product of the gene encoding the CCAAT-displacement protein transcription factor, is a Golgi membrane protein related to giantin

Gillingham, AK, Pfeifer, AC, Munro, S

Mol. Biol. Cell 2002
15718469 Golgin tethers define subpopulations of COPI vesicles

Malsam, J, Satoh, A, Pelletier, L, Warren, G

Science 2005
9915833 Identification and characterization of golgin-84, a novel Golgi integral membrane protein with a cytoplasmic coiled-coil domain

Bascom, RA, Srinivasan, S, Nussbaum, RL

J. Biol. Chem. 1999
11718716 Identification of rabaptin-5, rabex-5, and GM130 as putative effectors of rab33b, a regulator of retrograde traffic between the Golgi apparatus and ER

Valsdottir, R, Hashimoto, H, Ashman, K, Koda, T, Storrie, B, Nilsson, T

FEBS Lett. 2001
22013193 COPII and COPI traffic at the ER-Golgi interface

Szul, T, Sztul, E

Physiology (Bethesda) 2011
23091056 Ric1-Rgp1 complex is a guanine nucleotide exchange factor for the late Golgi Rab6A GTPase and an effector of the medial Golgi Rab33B GTPase

Pusapati, GV, Luchetti, G, Pfeffer, SR

J. Biol. Chem. 2012
20163571 Rab33b and Rab6 are functionally overlapping regulators of Golgi homeostasis and trafficking

Starr, T, Sun, Y, Wilkins, N, Storrie, B

Traffic 2010
15758030 Cisternal rab proteins regulate Golgi apparatus redistribution in response to hypotonic stress

Jiang, S, Storrie, B

Mol. Biol. Cell 2005
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