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Basic leucine zipper (bZIP) domain of CCAAT/enhancer-binding protein beta (CEBPB): a DNA-binding and dimerization domain CEBPB is a key regulator of metabolism, adipocyte differentiation, myogenesis, and macrophage activation. It is expressed as three distinct isoforms from an intronless gene through alternative translation initiation: CEBPB1 (or liver-enriched activator protein 1, LAP1); CEBPB2 (OR LAP2); and CEBPB3 (or liver-enriched inhibitory protein, LIP). LAP1/2 function as transcriptional activators while LIP is a repressor due to its lack of a transactivation domain. The relative expression of LAP and LIP has effects on inflammation, ER stress, and insulin resistance. CEBPs (or C/EBPs) are Basic leucine zipper (bZIP) transcription factors that regulate many cellular processes. There are six CEBP proteins in mammalian cells including CEBPA (alpha), CEBPB (beta), CEBPG (gamma), CEBPD (delta), and CEBPE (epsilon), which all contain highly conserved bZIP domains at their C-termini and variations at their N-terminal regions. bZIP factors act in networks of homo and heterodimers in the regulation of a diverse set of cellular processes. The bZIP structural motif contains a basic region and a leucine zipper, composed of alpha helices with leucine residues 7 amino acids apart, which stabilize dimerization with a parallel leucine zipper domain. Dimerization of leucine zippers creates a pair of the adjacent basic regions that bind DNA and undergo conformational change. Dimerization occurs in a specific and predictable manner resulting in hundreds of dimers having unique effects on transcription. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",