March 28, 2019

Unraveling endocytosis

New discoveries by Jason MacGurn and colleagues further understanding of the complex machinery that cells use take up substances from outside the cell.

by Niyati Vachharajani

Endocytosisis a highly regulated process in which cells take up substances packaged in vesicles by internalizing the plasma membrane surrounding the cargo.

In yeast, the enzyme Rsp5 regulates most endocytic events with the help of arrestin-related Rsp5 adaptor proteins called ARTs. Yet much remains to be learned about how this extraordinarily complex cellular machinery works.

Reporting this month in the Journal of Cell Biology, Jason MacGurn, PhD, and colleagues focus on the essential amino acid methionine.

They describe how an influx of methionine triggers the dephosphorylation, or removal of a phosphate group, from the Art1 adaptor protein by a Ppz phosphatase enzyme. Like turning on a switch, Art1 in turn recognizes and induces the endocytosis of a methionine transporter protein, Mup1.

These findings contribute to further understanding of the complex and highly coordinated endocytic trafficking mechanism, which is an essential part of many cellular processes including sodium resorption by the kidney and regulation of blood plasma sodium levels.

This research was supported by grants from the National Institutes of Health (CA119925, HL069765, GM101077, GM118491).