Liquid-like Protein Droplets Shape Cellular Membranes

April 08, 2021

Two recent papers authored by researchers from Jeanne Stachowiak’s lab describe new insights into cell behavior, which have the potential to improve understanding of how cellular membranes are shaped.

In a new paper published in PNAS, Feng Yuan, a third-year graduate student, has discovered a new mechanism that drives cellular membrane bending.

Membrane bending, or membrane curvature, is important because it’s the method cells use to take in materials and undergo cellular processes. In essence cellular membrane curvature acts like the UPS, packaging and shipping necessary cargo to other parts of cells and between cells.

Traditionally it was thought that structured proteins were responsible for curving membranes. But cells also contain proteins that lack shape, known as disordered proteins. Yuan’s study shows that liquid-like proteins, one type of disordered protein that hadn’t been studied in this capacity, can also shape and curve membranes. His discovery shows that membrane remodeling is not exclusive to structured proteins.

liquid like droplets
Liquid-like proteins bind to the outside of spherical vesicles. The tubules are formed by the assembly of liquid-like proteins. 

In another paper recently published by Nature Cell Biology, a study led by postdoctoral researcher Kasey Day shows that liquid-like proteins also initiate endocytosis, the process by which a cell takes in materials.

Day’s ongoing work is concerned with identifying general principles that govern how material is packaged into membrane vesicles, which are the primary vehicles for moving proteins and lipids around inside the cell.

“We can’t really be effective at drug delivery or understanding viruses that invade cells until we first understand the biophysical mechanisms cells use. Now that we know this is likely a general biophysical principle that governs cell trafficking, we can apply it in many different directions,” Day says.

The work in both papers essentially lays out an instruction manual of cell behavior that other researchers can use to better understand how curved membrane structures, such as transport vesicles, are formed inside the cell. Ultimately, this knowledge could be used to build effective drug delivery systems, better understand how viruses enter cells, and gain insights into signaling pathways that lead to disease.

Funding for research was provided by the National Institutes of Health, Human Frontiers Science Program, a National Science Foundation Graduate Research Fellowship, National Cancer Institute, and Texas State funds provided through the UTHSCSA Office of the Vice President for Research.