Webb M A, Cavaletto J M, Klanrit P, Thompson G A
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.
Cell Stress Chaperones. 2001 Jul;6(3):247-55. doi: 10.1379/1466-1268(2001)006<0247:oiatot>2.0.co;2.
The Hsp70-interacting protein Hip binds to the adenosine triphosphatase domain of Hsp70, stabilizing it in the adenosine 5'-diphosphate-ligated conformation and promoting binding of target polypeptides. In mammalian cells, Hip is a component of the cytoplasmic chaperone heterocomplex that regulates signal transduction via interaction with hormone receptors and protein kinases. Analysis of the complete genome sequence of the model flowering plant Arabidopsis thaliana revealed 2 genes encoding Hip orthologs. The deduced sequence of AtHip-1 consists of 441 amino acid residues and is 42% identical to human Hip. AtHip-1 contains the same functional domains characterized in mammalian Hip, including an N-terminal dimerization domain, an acidic domain, 3 tetratricopeptide repeats flanked by a highly charged region, a series of degenerate GGMP repeats, and a C-terminal region similar to the Sti1/Hop/p60 protein. The deduced amino acid sequence of AtHip-2 consists of 380 amino acid residues. AtHip-2 consists of a truncated Hip-like domain that is 46% identical to human Hip, followed by a C-terminal domain related to thioredoxin. AtHip-2 is 63% identical to another Hip-thioredoxin protein recently identified in Vitis labrusca (grape). The truncated Hip domain in AtHip-2 includes the amino terminus, the acidic domain, and tetratricopeptide repeats with flanking charged region. Analyses of expressed sequence tag databases indicate that both AtHip-1 and AtHip-2 are expressed in A thaliana and that orthologs of Hip are also expressed widely in other plants. The similarity between AtHip-1 and its mammalian orthologs is consistent with a similar role in plant cells. The sequence of AtHip-2 suggests the possibility of additional unique chaperone functions.
热休克蛋白70相互作用蛋白（Hip）与热休克蛋白70的腺苷三磷酸酶结构域结合，使其稳定在腺苷5'-二磷酸连接的构象中，并促进靶多肽的结合。在哺乳动物细胞中，Hip是细胞质伴侣异源复合物的一个组成部分，该复合物通过与激素受体和蛋白激酶相互作用来调节信号转导。对模式开花植物拟南芥的全基因组序列分析发现了2个编码Hip直系同源物的基因。AtHip-1的推导序列由441个氨基酸残基组成，与人类Hip的同源性为42%。AtHip-1包含与哺乳动物Hip相同的功能结构域，包括一个N端二聚化结构域、一个酸性结构域、3个由高电荷区域侧翼的四肽重复序列、一系列简并的GGMP重复序列以及一个与Sti1/Hop/p60蛋白相似的C端区域。AtHip-2的推导氨基酸序列由380个氨基酸残基组成。AtHip-2由一个截短的类Hip结构域组成，该结构域与人类Hip的同源性为46%，后面跟着一个与硫氧还蛋白相关的C端结构域。AtHip-2与最近在葡萄中鉴定出的另一种Hip-硫氧还蛋白的同源性为63%。AtHip-2中的截短Hip结构域包括氨基末端、酸性结构域以及带有侧翼电荷区域的四肽重复序列。对表达序列标签数据库的分析表明，AtHip-1和AtHip-2在拟南芥中均有表达，并且Hip的直系同源物在其他植物中也广泛表达。AtHip-1与其哺乳动物直系同源物之间的相似性表明其在植物细胞中可能具有类似的作用。AtHip-2的序列表明它可能具有额外的独特伴侣功能。
