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.
The transmembrane protein p23 contributes to the organization of the Golgi apparatus
M. Rojo, G. Emery, V. Marjomaki, A.W. McDowall, R.G. Parton, J. Gruenberg; The transmembrane protein p23 contributes to the organization of the Golgi apparatus. J Cell Sci 15 March 2000; 113 (6): 1043–1057. doi: https://doi.org/10.1242/jcs.113.6.1043
Download citation file:
Advertisement
Cited by
Reasons to submit to Journal of Cell Science

There are many benefits to publishing through Journal of Cell Science, follow this link to read more about our reasons to submit or visit our submission page now.
Call for papers: Cell and Tissue Polarity
-PolarityCFP.png?versionId=5150)
We are welcoming submissions for our next special issue, which will focus on ‘Cell and tissue polarity’ and will be guest edited by David Bryant. Submission deadline: 15 July.
The Forest of Biologists

The Forest of Biologists is a biodiversity initiative created by The Company of Biologists, with support from the Woodland Trust. For every Research and Review article published in Journal of Cell Science a native tree is planted in a UK forest. In addition to this we are protecting and restoring ancient woodland and are dedicating these trees to our peer reviewers. Visit our virtual forest to learn more.
Propose a new Workshop for 2025

Do you have an idea for a Workshop? We are now accepting proposals for our 2025 Biologists Workshops programme. As the scientific organiser, your involvement will be focused on the science. We'll take care of all the logistics. In 2025 we'll continue our efforts to diversify our Workshop programme and will be reserving one of our Workshops for an application from a Global South (GS) country to host an event overseas.
FocalPlane Image Competition 2023

FocalPlane’s 2023 image competition is underway, in celebration of the community site’s third birthday. Click here for submission details and information on how to showcase your favourite image.