Heat Shock Protein

HSP90B1 is an abundant molecular chaperone resident endoplasmic reticulum (ER) lumenal stress protein which is part of the Hsp90 family. HSP90B1 is involved in maintaining protein homeostasis in the secretory pathway as well as functioning in the intracellular trafficking of peptides from the extracellular space to the MHC class I antigen processing pathway of antigen presentation cells. HSP90B1 has key roles in signal transduction, protein folding, protein degradation, and morphologic evolution. HSP90B1 protein associates with numerous cochaperones and involved in folding of newly synthesized proteins or stabilizing and refolding denatured proteins after stress. HSP90B1 is highly expressed in human gastric carcinoma BGC-823 cells during the whole cell cycle.

HSP90B1 is an abundant molecular chaperone resident endoplasmic reticulum (ER) lumenal stress protein which is part of the Hsp90 family. HSP90B1 is involved in maintaining protein homeostasis in the secretory pathway as well as functioning in the intracellular trafficking of peptides from the extracellular space to the MHC class I antigen processing pathway of antigen presentation cells. HSP90B1 has key roles in signal transduction, protein folding, protein degradation, and morphologic evolution. HSP90B1 protein associates with numerous cochaperones and involved in folding of newly synthesized proteins or stabilizing and refolding denatured proteins after stress. HSP90B1 is highly expressed in human gastric carcinoma BGC-823 cells during the whole cell cycle.

HSP90 has been identified in the cytosol, nucleus and endoplasmic reticulum, and is reported to exist in many tissue types. In several tissues, including smooth muscle, HSP90 comprises up to 2% of total cellular protein. HSP90 functions as a dimer, assembled as part of heterocomplex. It possesses ATP-binding site and low ATPase activity. HSP90 is able to associate with actin filaments in certain conditions. Another important property of HSP90 is the binding of unoccupied steroid hormone receptors. HSP90 has been characterized as a molecular chaperone able to keep the target protein in a folding-competent state. It has an enhanced chaperone activity in oligomeric form at high temperatures. HSP90 function is sensitive to bivalent cations concentration.

HSP27 or Estrogen-Regulated 24K proteinis a part of the mammalian small heat shock protein family. The protein is expressed constitutively in many tissues and its expression is increased to high levels after different types of stress including high temperatures, toxic metals, drugs and oxidants. Furthermore, Hsp27 is phosphorylated in vivo on three phosphorylation sites (Ser15, Ser78 and Ser82) by protein kinases including MAPKAP kinase 2 and the stress-activated protein kinase SAPK2 (p38).

HSP27 (also known as the Estrogen-Regulated 24K protein, and hsp 28) is a member of the mammalian small heat shock protein family. Hsp27 is expressed constitutively in many tissues and its expression is increased to high levels after various types of stress including elevated temperatures, toxic metals, drugs and oxidants. Also, Hsp27 is phosphorylated in vivo on three phosphorylation sites (Ser15, Ser78 and Ser82) by protein kinases including MAPKAP kinase 2 and the stress-activated protein kinase SAPK2 (p38).

HSP27 (also known as the Estrogen-Regulated 24K protein, and hsp 28) is a member of the mammalian small heat shock protein family. Hsp27 is expressed constitutively in many tissues and its expression is increased to high levels after various types of stress including elevated temperatures, toxic metals, drugs and oxidants. Also, Hsp27 is phosphorylated in vivo on three phosphorylation sites (Ser15, Ser78 and Ser82) by protein kinases including MAPKAP kinase 2 and the stress-activated protein kinase SAPK2 (p38).

HSP104 is a molecular chaperone required for stress tolerance and for maintenance of [psi(+)] prions in the budding yeast Saccharomyces cerevisiae. Hsp104 can protect yeast cells against high temperature and high concentration of ethanol but mutation studies have shown this protein is not required for normal growth. Hsp104 was cloned into an E. coli expression vector and was purified to apparent homogeneity by using conventional column chromatography techniques.

Heat Shock Transcription Factor, Y-Linked 1 (HSFY1) is a member of the heat shock factor (HSF) family of transcriptional activators for heat shock proteins. HSFY1 is localizes to an area of chromosome Y which is from time to time deleted in infertile males and therefore is considered a gene for azoospermia. The genome has 2 identical duplicates of HSFY1 within a palindromic area.

HSF2BP, also known as HSF2 binding protein links with HSF2. This interaction takes place between the trimerization domain of HSF2 and the amino terminal hydrophilic region of HSF2BP which contains two leucine zipper motifs. Therefore, HSF2BP is involved in modulating HSF2 activation.

The transcription of heat-shock genes is rapidly induced after temperature stress in response to environmental changes, and it is also involved in oogenesis, spermatogenesis, and placental development. Hsp90, is a major repressor of HSF1 gene. HSF1 is known for its participation in heat shock response. HSF1 protein regulates the transcription of hundreds of targets, such as genes involved in protein folding, detoxification, energy generation, carbohydrate metabolism, and cell wall organization.
HSF1 binds to MTA1 in vitro & in breast carcinoma. Suppression of estrogen-dependent transcription may contribute to role of HSF1 in cancer.
Human cancer lines of diverse origins express higher dependence on HSF1 function to maintain proliferation and survival than their non-transformed counterparts.
HSF1 induces anticoagulation and relaxation factors in vascular endothelial cells and could therefore be used to treat cardiovascular disease. HSF1 is directly involved in the regulation of HO1 having an anti-oxidative role.
NF-kappaB and HSF1 are systemically activated in human acute pancreatitis.
HSF1 activation protects against severity of pancreatitis.
HSF is a vital transcription factor which plays a role in up-regulation of VDUP1 expression through stresses such as elevated density and serum deprivation cultures.

Heat Shock Factor Binding Protein 1-Like 1 (HSBP1L1) is a part of a family of eukaryotic proteins known as nucleotide exchange factors for HSP 70. HSBP1L1 is a protein coding gene whose expression is regulated mainly at the transcription level.

The heat-shock response is elicited by exposure of cells to thermal and chemical stress and through the activation of HSFs (heat shock factors) results in the elevated expression of heat-shock induced genes. Heat shock factor binding protein-1 (HSBP1), is a 76-amino-acid protein that binds to heat shock factor 1(HSF1), which is a transcription factor involved in the HS response. During HS response, HSF1 undergoes conformational transition from an inert non-DNA-binding monomer to active functional trimers. HSBP1 is nuclear-localized and interacts with the active trimeric state of HSF1 to negatively regulate HSF1 DNA-binding activity. Overexpression of HSBP1 in mammalian cells represses the transactivation activity of HSF1. When overexpressed in C.elegans HSBP1 has severe effects on survival of the animals after thermal and chemical stress consistent with a role of HSBP1 as a negative regulator of heat shock response.

SERPINH1 is part of the serpin superfamily of serine proteinase inhibitors. SEPINH1 expression is induced by heat shock. HSP47 localizes to the endoplasmic reticulum lumen and binds collagen therefore it is a molecular chaperone which takes part in the maturation of collagen molecules, facilitating the folding and assembly of procollagen molecules, retaining unfolded molecules within the ER, and assisting the transport of correctly folded-molecules from the ER to Golgi apparatus. Autoantibodies to HSP47 protein have been found in rheumatoid arthritis. SERPINH1 binds specifically to collagen and acts as a chaperone in the biosynthetic pathway of collagen.

AHA1 is a cochaperone that stimulates hsp90 ATPase activity. AHSA1 binds the middle domain of Hsp90 (amino acid 272-627) and functions as an ATPase-activating protein that competes with p23 and other co-chaperones for Hsp90 binding.
AHA1 affects a step in the endoplasmic reticulum to golgi trafficking.

Escherichia coli Hsp31 (HchA) is a homodimeric member of the ThiI/DJ-1/PfpI superfamily which combines molecular chaperone and aminopeptidase activities. HchA uses temperature-induced exposure of structured hydrophobic domains to capture and stabilize early unfolding protein intermediates under severe thermal stress.