DNA Recognition by Helix-Loop-Helix Proteins

摘要: The helix-loop-helix proteins are characterized by a highly conserved 60-100 residue motif comprised of two amphipathic α-helices separated loop variable length, and amino acid composition sequence. These motifs dimerize approximating the hydrophobic faces α-helices, forming left-handed, parallel, four-helix bundle. Baltimore coworkers (Murre et al. 1989) first described conservation this feature in large number eukaryotic transcription factors, implicated it dimerization DNA binding. Subsequent work has confirmed their bold prediction demonstrated that is primarily responsible for dimerization. Most possess basic region immediately N-terminal to helix (Prendergast Ziff 1989), which mediates high-affinity, specific binding (reviewed Bexevanis Vinson 1993). In addition, second many these factors extended beyond C-terminus fourhelix bundle, where leucine heptad repeat or zipper forms coiled-coil dimer interface. Finally, some lack (Benezra 1990).