| abstract |
Kruppel-like factor (KLF) 9, KLF13, KLF14, KLF16, and similar proteins. Kruppel-like factor 9 (KLF9; also known as Krueppel-like factor 9, or Basic Transcription Element Binding Protein 1/BTEB Protein 1) is a protein that in humans is encoded by the KLF9 gene. KLF9 is critical for the inhibition of growth and development of tumors. It is involved in cell differentiation of B cells, keratinocytes, and neurons. It is also a key transcriptional regulator for uterine endometrial cell proliferation, adhesion, and differentiation; these are processes essential for pregnancy success and are subverted during tumorigenesis. KLF9, KLF10, KLF11, KLF13, KLF14, and KLF16 share a conserved alpha-helical motif AA/VXXL that mediates their binding to Sin3A and their activities as transcriptional repressors. KLF9 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 KLF9. |