N-terminal domain of Kruppel-like factor 3Kruppel-like factor 3 (KLF3; also called Krueppel-like factor 3 and originally called Basic Kruppel-like Factor/BKLF), was the third member of the KLF family of zinc finger transcription factors to be discovered. KLF3 possesses a wide range of biological impacts on regulating apoptosis, differentiation, and proliferation in various tissues during the entire progression process. It has been proposed as a tumor suppressor in colorectal cancer. It appears to function predominantly as a repressor of transcription, turning genes off by recruiting the C-terminal Binding Protein co-repressors CtBP1 and CtBP2. CtBP docks onto a short motif (residues 61-65) in the N-terminus of KLF3, through the Proline-X-Aspartate-Leucine-Serine (PXDLS) motif. CtBP in turn recruits histone modifying enzymes to alter chromatin and repress gene expression. KLF3 belongs to a family of proteins, called the Specificity Protein (SP)/KLF family, characterized by a C-terminal DNA-binding domain of 81 amino acids consisting of three Kruppel-like C2H2 zinc fingers. These factors bind to a loose consensus motif, namely NNRCRCCYY (where N is any nucleotide; R is A/G, and Y is C/T), such as the recurring motifs in GC and GT boxes (5'-GGGGCGGGG-3' and 5-GGTGTGGGG-3') that are present in promoters and more distal regulatory elements of mammalian genes. Members of the KLF family can act as activators or repressors of transcription depending on cell and promoter context. KLFs regulate various cellular functions, such as proliferation, differentiation, and apoptosis, as well as the development and homeostasis of several types of tissue. In addition to the C-terminal DNA-binding domain, each KLF also has a unique N-terminal activation/repression domain that confers specificity and allows it to bind specifically to a certain partner, leading to distinct activities in vivo. This model represents the N-terminal domain of KLF3.