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Query: UNIPROT:P06889 (Mol)
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A pea cDNA clone, PHSP1, encoding a member of the HSP70 gene family has been isolated. DNA sequence analysis indicates that the protein encoded by PHSP1 is a homologue of the mitochondrial HSP70 proteins, SSP1 from Schizosaccharomyces pombe and SSC1 from S. cerevisiae. It contains an amino-terminal extension of 50 amino acids, rich in basic and hydroxyl amino acids, similar to other plant mitochondrial leader sequences. Western blot analysis indicates that the PHSP1 protein is associated only with mitochondria and not with any other sub-cellular organelle or cytoplasm. Further confirmation of its location within mitochondria was obtained from in vitro protein translocation experiments into purified Pisum sativum mitochondria. It was observed that the precursor protein was efficiently imported and that it is processed to produce a protein with an Mr of the anticipated size of the mature protein. Results are discussed with respect to the structure and function of the mitochondrial HSP70 protein.
Plant Mol Biol 1992 Jan
PMID:Characterisation of PHSP1, a cDNA encoding a mitochondrial HSP70 from Pisum sativum. 173 75

Human progesterone receptors (PR) were overexpressed in Spodoptera frugiperda (Sf9) insect cells using a recombinant baculovirus system. Recombinant viruses were constructed that produced either full-length A (94K) or B (120K) forms of human PR, and each was expressed as a functional protein. Steroid and DNA binding activities were found to be indistinguishable from that of endogenous human PR in T47D breast cancer cells. Moreover, as analyzed by gel-mobility shift, recombinant PR-A and PR-B each bound to specific progesterone response elements in a strictly hormone-dependent manner. Native receptors expressed in Sf9 cells also exhibited structural properties similar to that of endogenous PR. Cytosolic PR (PR-A or PR-B), prepared in low salt buffer, sedimented on density gradients as an 8S oligomeric complex that was converted largely to 4S by treatment with 0.4 M NaCl. Immune isolation of the 8S cytosol PR complex and analysis of protein composition revealed the presence of two specific copurifying proteins of approximately 90K and 70K. The 90-K component was identified immunologically as heat shock protein 90. The 70-K component was not identified but is likely to be the insect equivalent of heat shock protein 70. Immune isolation of PR from Sf9 cells metabolically labeled with [32Pi], revealed that expressed PR was capable of being phosphorylated in insect cells. Hormone addition to Sf9 cells, however, did not stimulate the same increase in PR phosphorylation or upshift in mobility on sodium dodecyl sulfate gels that occurs with endogenous receptors in T47D cells. Thus some, but not all, phosphorylations occur with human PR expressed in Sf9 cells. These phosphorylation data, together with the fact that expressed PR required hormone for DNA binding, indicate that the hormone-dependent phosphorylation step responsible for PR upshifts on sodium dodecyl sulfate-polyacrylamide gel electrophoresis is not required for receptor binding to DNA. The baculovirus expression system, therefore, may prove valuable in dissecting the functional role(s) for both hormone-dependent and hormone-independent PR phosphorylation.
Mol Endocrinol 1991 Nov
PMID:Characterization and functional properties of the A and B forms of human progesterone receptors synthesized in a baculovirus system. 177 77

The molecular karyotypes of several Leishmania isolates (Leishmania amazonensis, Leishmania braziliensis, Leishmania guyanensis, Leishmania panamensis, Leishmania donovani, Leishmania major, Leishmania aethiopica, Leishmania tropica, Leishmania enriettii) have been analyzed by clamped homogeneous electric field (CHEF) gel electrophoresis. The chromosomal localization of genes encoding 2 major surface glycoproteins, gp63 and gp46/M2, heat shock protein 70 (hsp70), and beta-tubulin was determined for cloned isolates of 8 of these Leishmania species. The chromosome size class assignment of hsp70 genes was most conserved in that all species contained a single hybridizing DNA band of approximately 1200 kb. The beta-tubulin gene probe hybridized predominantly to large (1600-1750 kb) chromosome-size DNA and to 1-5 additional bands, the number of which depended on the species. The number and size of DNA bands hybridizing to gp63 or gp46/M2 gene probes were not uniformly conserved among species. In contrast to previous reports of gp63 genes being located on a single chromosome, using various CHEF gel conditions we observed a Leishmania major gp63 gene probe hybridizing to at least 2 chromosomal DNA bands in the New World species and in L. tropica. Gp46/M2 genes were located on 1 band in L. donovani, L. major, and L. aethiopica or 2 bands in L. tropica and L. amazonensis, but surprisingly, do not hybridize to any chromosomal DNA of species in the L. braziliensis complex or in L. enriettii. Whenever both genes were present in a species, gp63 and gp46/M2 genes were located on different chromosomal DNA bands.
Mol Biochem Parasitol 1991 Sep
PMID:Molecular karyotype and chromosomal localization of genes encoding two major surface glycoproteins, gp63 and gp46/M2, hsp70, and beta-tubulin in cloned strains of several Leishmania species. 177 88

We investigated the recognition of the conserved 5-bp repeated motif NGAAN, which occurs in heat shock gene promoters of Drosophila melanogaster and other eukaryotic organisms, by human heat shock transcription factor (HSF). Extended heat shock element mutants of the human HSP70 gene promoter, containing additional NGAAN blocks flanking the original element, showed significantly higher affinity than the wild-type promoter element for human HSF in vitro. Protein-DNA contact positions were identified by hydroxyl radical protection, diethyl pyrocarbonate interference, and DNase I footprinting. New contacts in the mutant HSE constructs corresponded to the locations of additional NGAAN motifs. The pattern of binding indicated the occurrence of multiple DNA binding modes for HSF with the various constructs and was consistent with an oligomeric, possibly trimeric, structure of the protein. In contrast to the improved binding, the extended heat shock element mutant constructs did not exhibit dramatically increased heat-inducible transcription in transient expression assays with HeLa cells.
Mol Cell Biol 1991 Jul
PMID:Modular recognition of 5-base-pair DNA sequence motifs by human heat shock transcription factor. 190 40

A portion of the RNA genome of beet yellows closterovirus (BYV) has been sequenced encompassing a complete long open reading frame (ORF) potentially encoding a 65 kDa protein. The sequence of this putative protein was strikingly similar to those of HSP70-related heat shock proteins. The counterparts of all the eight segments strongly conserved in HSP70s could be confidently identified in the BYV 65 kDa protein. It is suggested that some of these segments might be the ATP-binding site(s) and that, similarly to the heat shock proteins, the 65 kDa is probably ATP-binding. Generally, however, the divergence between the 65 kDa sequence and the sequences of the HSP70s was much more pronounced than that between any two members of the latter family, allowing a clearer delineation of clusters of conserved residues that might be crucial for protein function. It is suggested that these observations will be helpful in functional dissection of the proteins of the HSP70 family. Analysis of the sequence of a portion of the ORF found upstream from the 65 kDa ORF showed that the C-terminal domain of the encoded protein could be an RNA-dependent RNA polymerase closely related to those of tricornaviruses, a family of RNA plant viruses with three component genomes.
J Mol Biol 1991 Feb 20
PMID:Putative 65 kDa protein of beet yellows closterovirus is a homologue of HSP70 heat shock proteins. 200 13

We have analyzed 41 deletion, linker scan, and substitution mutants of the human HSP70 gene promoter for activation by the adenovirus E1a region. No natural element of the HSP70 gene promoter was required for activation. To investigate specific interactions between E1a and transcription factors, a set of 24 promoters containing all possible combinations of eight different upstream or TATA motifs was investigated for E1a stimulation. E1a transactivated the promoter regardless of the particular TATA motif present. Furthermore, there was no dramatic correlation between any upstream motif and activation by E1a. These data suggest that E1a does not stimulate transcription via an interaction with any specific transcription factor but instead suggest that E1a interacts via the general transcription machinery.
Mol Cell Biol 1990 Jan
PMID:E1a transactivation of human HSP70 gene promoter substitution mutants is independent of the composition of upstream and TATA elements. 215 62

Regional localization of HSP70 expression in brain of rats exposed to increased ambient temperatures was examined using in situ hybridization. In addition to the cerebellar granule cell layer and choroid plexus, selective hybridization was observed in the hippocampal dentate gyrus, paraventricular and dorsomedial hypothalamic nuclei, median eminence, and medial habenula. Apparently, cells in brain regions coordinating the neuroendocrine response to stress show a preferential induction of cellular stress proteins in response to heat.
Brain Res Mol Brain Res 1990 Jun
PMID:In vivo hyperthermia induces expression of HSP70 mRNA in brain regions controlling the neuroendocrine response to stress. 216 5

The SSA3 gene of Saccharomyces cerevisiae, a member of the HSP70 multigene family, is expressed at low levels under optimal growth conditions and is dramatically induced in response to heat shock. Sequences coinciding with two overlapping heat shock elements, located 156 base pairs upstream of the transcribed region, were necessary and sufficient for regulation of heat induction. The SSA3 promoter was also activated in an ssa1ssa2 double-mutant strain. This increase in the expression of SSA3 was mediated via the same upstream activating sequences that activated transcription in response to heat shock.
Mol Cell Biol 1990 Jun
PMID:Transcriptional regulation of SSA3, an HSP70 gene from Saccharomyces cerevisiae. 218 13

Changes in environmental temperature regulate the differential expression of genes during Leishmania stage differentiation. Therefore, molecular analysis of the heat shock proteins (HSPs) in these parasites is of interest as a model for thermoregulation of gene expression. Sequences of the HSP83 repetitive unit in the genome of Leishmania mexicana amazonensis, including both the coding and intergenic regions, are described. The 5' boundary of the message was mapped by S1 analysis, to potential AG splice sites located 293, 295 and 321 nucleotides upstream of the first ATG. A high degree of conservation (84%) is present between the coding sequence of HSP83 from L. mexicana amazonensis and similar sequences from Trypanosoma cruzi. The intergenic leishmanial sequences, however, were not homologous to similar sequences from HSP83 of trypanosomes, or from HSP70 of Leishmania major. A search for sequences that resemble eukaryote thermoregulated promoters was made and several regions with dyad symmetry were detected. However, only one of these regions was partially homologous with the consensus heat shock element present upstream of all eukaryotic HSPs studied to date.
Mol Biochem Parasitol
PMID:Sequence analysis and transcriptional activation of heat shock protein 83 of Leishmania mexicana amazonensis. 227 Jan 7

To investigate interactions between transcription factors on mammalian promoters, we constructed a set of 24 variations of the human HSP70 gene promoter in which six upstream sequence motifs are paired in every possible combination with four TATA motifs. These promoters were analyzed for in vivo expression, and selected constructs were examined by in vitro template commitment studies. Activation transcription factor (ATF) and CP1 showed dramatically different interactions with the factor(s) bound to the TATA region. CP1 functioned in vivo regardless of the TATA motif that it was paired with and was not capable of sequestering the core promoter complex in a template commitment assay. ATF activity was dramatically altered by changing the TATA motif, and ATF was able to sequester the core promoter complex. These data suggest that CP1 and ATF function by distinct mechanisms that differ with respect to interaction with the factor(s) at the TATA box. Factor Sp1 also appeared to function by a TATA-independent mechanism. These data imply that the ability of a factor to function is determined not only by the intrinsic properties of the factor but also by promoter context.
Mol Cell Biol 1990 Jan
PMID:Factor substitution in a human HSP70 gene promoter: TATA-dependent and TATA-independent interactions. 229 2


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