title: Orthologs in Arabidopsis thaliana of the Hsp70 interacting protein Hip.
abstract: 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.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA. webb@btny.purdue.edu
authors.forename: M A
authors.initials: MA
authors.lastname: Webb
authors.forename: J M
authors.initials: JM
authors.lastname: Cavaletto
authors.forename: P
authors.initials: P
authors.lastname: Klanrit
authors.forename: G A
authors.initials: GA
authors.lastname: Thompson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D016415:Sequence Alignment; D027843:Vitis / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; C452501:HIP proteins, Arabidopsis; D018840:HSP70 Heat-Shock Proteins; C105426:Hip chaperone; D018832:Molecular Chaperones