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Rojo M, Emery G, Marjomäki V, McDowall AW, Parton RG, Gruenberg J. The transmembrane protein p23 contributes to the organization of the Golgi apparatus. J Cell Sci 2000; 113 ( Pt 6):1043-57. [PMID: 10683152 DOI: 10.1242/jcs.113.6.1043] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In previous studies we have shown that p23, a member of the p24-family of small transmembrane proteins, is highly abundant in membranes of the cis-Golgi network (CGN), and is involved in sorting/trafficking in the early secretory pathway. In the present study, we have further investigated the role of p23 after ectopic expression. We found that ectopically expressed p23 folded and oligomerized properly, even after overexpression. However, in contrast to endogenous p23, exogenous p23 molecules did not localize to the CGN, but induced a significant expansion of characteristic smooth ER membranes, where they accumulated in high amounts. This ER-derived, p23-rich subdomain displayed a highly regular morphology, consisting of tubules and/or cisternae of constant diameter, which were reminiscent of the CGN membranes containing p23 in control cells. The expression of exogenous p23 also led to the specific relocalization of endogenous p23, but not of other proteins, to these specialized ER-derived membranes. Relocalization of p23 modified the ultrastructure of the CGN and Golgi membranes, but did not affect anterograde and retrograde transport reactions to any significant extent. We conclude (i) that p23 has a morphogenic activity that contributes to the morphology of CGN-membranes; and (ii) that the presence of p23 in the CGN is necessary for the proper organization of the Golgi apparatus.
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Affiliation(s)
- M Rojo
- Department of Biochemistry, University of Geneva, Switzerland
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Quina FH, Hinze WL. Surfactant-Mediated Cloud Point Extractions: An Environmentally Benign Alternative Separation Approach. Ind Eng Chem Res 1999. [DOI: 10.1021/ie980389n] [Citation(s) in RCA: 333] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Frank H. Quina
- Department of Chemistry, Wake Forest University, P.O. Box 7486, Winston-Salem, North Carolina 27109
| | - Willie L. Hinze
- Department of Chemistry, Wake Forest University, P.O. Box 7486, Winston-Salem, North Carolina 27109
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