The labs of Tanja Mittag, PhD at St. Jude and Rohit Pappu, PhD, the Gene K. Beare Distinguished Professor of biomedical engineering at the McKelvey School of Engineering, created a stickers-and-spacers model to discern the rules underlying the driving forces for phase separation. The “stickers” and “spacers” are different types of amino acids along the protein chain.
The valence, or number, of stickers and the linear arrangement of stickers versus spacers has been shown by the Mittag and Pappu labs to have an impact on phase separation.
Building on that work, the Mittag and Pappu labs have uncovered a hierarchy of sticker and spacer interactions, gleaned using evolutionary analysis, and affirmed using biophysical measurements and physical theories. A new result to emerge is the role of net charge and the imbalance of charged amino acids on the driving forces for phase separation.
A paper on the work was published Dec. 20 in the journal Nature Chemistry.