Endoplasmic reticulum/Golgi-dependent protein secretion depends on signal peptides that mediate membrane translocation of nascent secretory proteins into the lumen of the endoplasmic reticulum. Classical secretory proteins are transported across the membrane of the endoplasmic reticulum in an unfolded conformation, which is similar to protein import into mitochondria. This process is mediated by Sec61, the protein-conducting channel of the endoplasmic reticulum. Employing both FACS-based in vivo transport assays and confocal microscopy, we now show that fibroblast growth factor 2 (FGF-2), a pro-angiogenic mediator exported from mammalian cells by an unconventional secretory pathway, does not need to be unfolded in order to be released into the extracellular space. These findings suggest that the molecular apparatus mediating export of FGF-2 is not only distinct from classical translocation machineries in terms of molecular identity but also operates in a mechanistically distinct manner that allows membrane translocation of FGF-2 in a folded conformation.
JCS fast-track option
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Special Issue – Cell Biology of Mitochondria
Our special issue on ‘Cell Biology of Mitochondria’ is now complete. Explore this issue and read the Editorial from our Guest Editors Ana J. García-Sáez and Heidi McBride.
Save the date – Imaging Cell Dynamics
We are delighted to announce that we will be hosting a 2026 Imaging Cell Dynamics meeting. This meeting will provide a unique opportunity to bring together experts working at the interface between cell biology and imaging. Save the date for 11-14 May 2026 and register for more information.
Origin and evolution of mitochondrial inner membrane composition
In this Review, Kailash Venkatraman and colleagues provide an examination of the morphological similarities between prokaryotic intracytoplasmic membranes and mitochondrial inner membranes, and whether cristae evolution has driven specialisation of the mitochondrial lipidome.
Resolution in super-resolution microscopy
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