14-3-3 theta/tau (theta in mice, tau in human), an isoform of 14-3-3 protein
14-3-3 tau/theta (tau in humans, theta in mice) isoform (also known as tyrosine 3-monooxygenase/ tryptophan 5-monooxygenase activation protein, theta polypeptide) is encoded by the YWHAQ gene in humans and plays an important role in controlling apoptosis through interactions with ASK1, c-jun NH-terminal kinase, and p38 mitogen-activated protein kinase (MAPK). Its interaction with CDC25c regulates entry into the cell cycle and subsequent interaction with Bad prevents apoptosis. 14-3-3 theta protein expression is induced in patients with amyotrophic lateral sclerosis. 14-3-3 tau is often overexpressed in breast cancer, which is associated with the downregulation of p21, a p53 target gene, and thus leads to tamoxifen resistance in MCF7 breast cancer cells and shorter patient survival. Therefore, 14-3-3 tau may be a potential therapeutic target in breast cancer. Additionally, 14-3-3 theta mediates nucleocytoplasmic shuttling of the coronavirus nucleocapsid protein which causes severe acute respiratory syndrome. 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.