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Gene Review

HSP90B1  -  heat shock protein 90kDa beta (Grp94),...

Sus scrofa

Synonyms: GRP94, Gp96, TRA1, ppk98
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Disease relevance of TRA1


High impact information on TRA1

  • Cells expressing a 524-base pair antisense grp78 fragment (pkASgrp78) had a diminished capacity to up-regulate grp78 and grp94 expression after ER stress [2].
  • Glucose-regulated protein of 94 kDa (GRP94), the endoplasmic reticulum Hsp90, is highly homologous to cytosolic Hsp90 [3].
  • In the current study, the structural and regulatory consequences of adenosine nucleotide binding to GRP94 were investigated [3].
  • On the basis of these data, we propose that structural maturation of the client protein substrate, rather than ATP binding or hydrolysis, serves as the primary signal for dissociation of GRP94-client protein complexes [3].
  • To identify a role(s) for ATP or ADP in the regulation of GRP94-client protein interactions, immunoglobulin (Ig) heavy chain folding intermediates containing bound GRP94 and immunoglobulin binding protein (BiP) were isolated from myeloma cells, and the effects of adenosine nucleotides on chaperone-Ig heavy chain interactions were examined [3].

Biological context of TRA1

  • Structural studies of recombinant fusion protein constructs yielded identification of a 44 amino acid domain that displayed autonomous dimerization activity and conferred a highly elongated structure, characteristic of native GRP94, to the fusion protein [4].
  • However, these cells were resistant to IDAM-induced apoptosis and had increased basal levels of Grp94 and a KDEL-containing protein of about 50 kDa [5].
  • Current experimental evidence indicates that GRP94 functions in an as yet undefined manner in protein folding and assembly in the ER [6].
  • Heterogeneity in the migration of purified GRP94 on native and denaturing PAGE was observed and demonstrated to reflect variability in the N-linked glycosylation state of the protein [6].

Anatomical context of TRA1


Associations of TRA1 with chemical compounds


Analytical, diagnostic and therapeutic context of TRA1

  • Velocity sedimentation and gel filtration chromatography were used to identify native GRP94 as a dimer with an extended, rod-like shape [4].
  • Analysis of GRP94 secondary structure by circular dichroism spectroscopy indicated an identical alpha-helical content for the native, chemically denatured/renatured, and heat-shocked forms of GRP94 [1].
  • These data, combined with molecular dimensions obtained from rotary shadowing electron microscopy, provide a structural model of GRP94 and identify the molecular basis of GRP94 self-assembly [4].
  • Western blot revealed the induction of GRP78, GRP94, and protein disulfide isomerase at wk 3 and 4 [8].


  1. Structural transitions accompanying the activation of peptide binding to the endoplasmic reticulum Hsp90 chaperone GRP94. Wearsch, P.A., Voglino, L., Nicchitta, C.V. Biochemistry (1998) [Pubmed]
  2. Endoplasmic reticulum chaperones GRP78 and calreticulin prevent oxidative stress, Ca2+ disturbances, and cell death in renal epithelial cells. Liu, H., Bowes, R.C., van de Water, B., Sillence, C., Nagelkerke, J.F., Stevens, J.L. J. Biol. Chem. (1997) [Pubmed]
  3. Adenosine nucleotides and the regulation of GRP94-client protein interactions. Rosser, M.F., Trotta, B.M., Marshall, M.R., Berwin, B., Nicchitta, C.V. Biochemistry (2004) [Pubmed]
  4. Endoplasmic reticulum chaperone GRP94 subunit assembly is regulated through a defined oligomerization domain. Wearsch, P.A., Nicchitta, C.V. Biochemistry (1996) [Pubmed]
  5. Distinct endoplasmic reticulum signaling pathways regulate apoptotic and necrotic cell death following iodoacetamide treatment. van De Water, B., Wang, Y., Asmellash, S., Liu, H., Zhan, Y., Miller, E., Stevens, J.L. Chem. Res. Toxicol. (1999) [Pubmed]
  6. Purification and partial molecular characterization of GRP94, an ER resident chaperone. Wearsch, P.A., Nicchitta, C.V. Protein Expr. Purif. (1996) [Pubmed]
  7. Gp96/GRP94 is a putative high density lipoprotein-binding protein in liver. de Crom, R., van Haperen, R., Janssens, R., Visser, P., Willemsen, R., Grosveld, F., van der Kamp, A. Biochim. Biophys. Acta (1999) [Pubmed]
  8. Scurvy leads to endoplasmic reticulum stress and apoptosis in the liver of Guinea pigs. Margittai, E., Bánhegyi, G., Kiss, A., Nagy, G., Mandl, J., Schaff, Z., Csala, M. J. Nutr. (2005) [Pubmed]
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