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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, metabolic regulation and apoptosis. More than 300 binding partners of the 14-3-3 domain have been identified in all subcellular compartments and include transcription factors, signaling molecules, tumor suppressors, biosynthetic enzymes, cytoskeletal proteins and apoptosis factors. 14-3-3 binding can alter the conformation, localization, stability, phosphorylation state, activity as well as molecular interactions of a target protein. They function only as dimers, some preferring strictly homodimeric interaction, while others form heterodimers. Binding of the 14-3-3 domain to its target occurs in a phosphospecific manner where it binds to one of two consensus sequences of their target proteins; RSXpSXP (mode-1) and RXXXpSXP (mode-2). In some instances, 14-3-3 domain containing proteins are involved in regulation and signaling of a number of cellular processes in phosphorylation-independent manner. Many organisms express multiple isoforms: there are seven mammalian 14-3-3 family members (beta, gamma, eta, theta, epsilon, sigma, zeta), each encoded by a distinct gene, while plants contain up to 13 isoforms. The flexible C-terminal segment of 14-3-3 isoforms shows the highest sequence variability and may significantly contribute to individual isoform uniqueness by playing an important regulatory role by occupying the ligand binding groove and blocking the binding of inappropriate ligands in a distinct manner. Elevated amounts of 14-3-3 proteins are found in the cerebrospinal fluid of patients with Creutzfeldt-Jakob disease. In protozoa, like Plasmodium or Cryptosporidium parvum 14-3-3 proteins play an important role in key steps of parasite development. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",