Roads and hubs of unconventional protein secretion

In eukaryotes, there is now compelling evidence that in addition to the conventional endoplasmic reticulum-Golgi secretory pathway, there are additional routes for the export of cytoplasmic proteins with a critical role in numerous physiopathological conditions. These alternative secretory pathways or unconventional protein secretion (UPS) start now to be molecularly dissected, and while UPS landscape appears to be governed by a striking diversity and heterogeneity of mechanisms, common principles are emerging. We review here the role of key molecular determinants as well as the role of central hubs for UPS, highlighting the plasticity and dynamic properties of membrane-bound compartments. We also describe recent findings that position UPS as an integral component of adaptive responses to cope with particular cellular needs and stresses.

Automated summary

There are multiple routes for protein secretion in eukaryotes, known as unconventional protein secretion (UPS), in addition to the conventional endoplasmic reticulum-Golgi secretory pathway. These UPS mechanisms are diverse but share common principles, and they play a significant role in adaptive responses to specific cellular needs and stresses.