Figure 21.13 All HLH proteins have regions corresponding to helix 1 and helix 2,separated by a loop of 10-24 residues.Basic HLH proteins have a region with conserved positive charges immediately adjacent to helix 1. MyoD Ala Asp Arg Arg Lys Ala Ala Thr Met Arg Gln ArgArg Arg Basic region Id Arg Leu Pro Ala LeuLeu Asp GIn Glu Glu Val Asn Val Leu 6 conserved residues are absent from ld MyoD Leu Ser Lys Val Asn GIn AlaPhe Gin Thr Leu Lys Arg Cys Thr Helix 1 Id Leu Tyr Asp Met Asn Gly Cys Tyr Ser Arg LeLys Gln Leu Val Conserved residues are found in both MyoD and Id MyoD LysVal Ginle Leu Arg AsnAla lle Arg Tylle GIn Gly LeuG Helix2 Id LysVal Gne Leu Gu His Vall AspTyreArg AspLe
亮氨酸拉链结构 • 亮氨酸拉链是一个富含亮氨酸残基的结 构域，参与形成二聚体。在每个拉链蛋 白中都有一个与重复的亮氨酸相邻的高 碱性区，该区可能含一个DNA结合点。 • 亮氨酸拉链形成的二聚体构成茎，分叉 对称的两个碱性区形成臂，与DNA结合。 这种结构称为bZIP基序
亮氨酸拉链结构 • 亮氨酸拉链是一个富含亮氨酸残基的结 构域，参与形成二聚体。在每个拉链蛋 白中都有一个与重复的亮氨酸相邻的高 碱性区，该区可能含一个DNA结合点。 • 亮氨酸拉链形成的二聚体构成茎，分叉 对称的两个碱性区形成臂，与DNA结合。 这种结构称为bZIP基序
Figure 21.15 The basic regions of the bZIP motif are held together by the dimerization at the adjacent zipper region when the hydrophobic faces of two leucine zippers interact in parallel orientation. Leucines on hydrophobic faces of helices interact Basic region Basic region binds DNA binds DNA Subunit 1 Subunit 2
• 亮氨酸拉链结构解释了为什么这种蛋白质 的目标序列总是没有间隔的反向重复序列
• 亮氨酸拉链结构解释了为什么这种蛋白质 的目标序列总是没有间隔的反向重复序列