14-3-3 domain; 14-3-3 domain is an essential part of 14-3-3 proteins, a ubiquitous class of regulatory, phosphoserine/threonine-binding proteins found in all eukaryotic cells, including yeast, protozoa and mammalian cells. 14-3-3 proteins play important roles in many biological processes that are regulated by phosphorylation, including cell cycle regulation, cell proliferation, protein trafficking