2024-03-29T15:00:00Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/202162021-12-27T16:23:22Zcom_10261_134com_10261_1col_10261_387
Cárdenas, Jesús
Rivero, Sabrina
Goud, Bruno
Bornens, Michel
Ríos, Rosa M.
2010-01-20T12:58:14Z
2010-01-20T12:58:14Z
2009-08
BMC Biology 7(56): (2009)
1741-7007
http://hdl.handle.net/10261/20216
10.1186/1741-7007-7-56
19715559
Background: The Golgi apparatus in mammals appears as a ribbon made up of interconnected
stacks of flattened cisternae that is positioned close to the centrosome in a microtubule-dependent
manner. How this organisation is achieved and retained is not well understood. GMAP210 is a long
coiled-coil cis-Golgi associated protein that plays a role in maintaining Golgi ribbon integrity and
position and contributes to the formation of the primary cilium. An amphipathic alpha-helix able to
bind liposomes in vitro has been recently identified at the first 38 amino acids of the protein
(amphipathic lipid-packing sensor motif), and an ARF1-binding domain (Grip-related Arf-binding
domain) was found at the C-terminus. To which type of membranes these two GMAP210 regions
bind in vivo and how this contributes to GMAP210 localisation and function remains to be
investigated.
Results: By using truncated as well as chimeric mutants and videomicroscopy we found that both
the N-terminus and the C-terminus of GMAP210 are targeted to the cis-Golgi in vivo. The ALPS
motif was identified as the N-terminal binding motif and appeared concentrated in the periphery of
Golgi elements and between Golgi stacks. On the contrary, the C-terminal domain appeared
uniformly distributed in the cis-cisternae of the Golgi apparatus. Strikingly, the two ends of the
protein also behave differently in response to the drug Brefeldin A. The N-terminal domain
redistributed to the endoplasmic reticulum (ER) exit sites, as does the full-length protein, whereas
the C-terminal domain rapidly dissociated from the Golgi apparatus to the cytosol. Mutants
comprising the full-length protein but lacking one of the terminal motifs also associated with the
cis-Golgi with distribution patterns similar to those of the corresponding terminal end whereas a
mutant consisting in fused N- and C-terminal ends exhibits identical localisation as the endogenous
protein.
Conclusion: We conclude that the Golgi localisation of GMAP210 is the result of the combined
action of the two N- and C-terminal domains that recognise different sub-regions of the cis-GA.
Based on present and previous data, we propose a model in which GMAP210 would participate in
homotypic fusion of cis-cisternae by anchoring the surface of cisternae via its C-terminus and
projecting its distal N-terminus to bind the rims or to stabilise tubular structures connecting
neighbouring cis-cisternae.
eng
openAccess
Golgi localisation of GMAP210 requires two distinct cis-membrane binding mechanisms
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