Disease relevance of Hspe1

• GroES, the cpn10 from Escherichia coli, is composed of seven 10kDa subunits, which form a dome-like oligomeric ring structure [1].
• In order to study whether these unfolding-refolding characteristics were conserved in other cpn10 proteins, we have examined the structural stabilities of cpn10s from rat mitochondria (RatES) and from hyperthermophilic eubacteria Thermotoga maritima (TmaES), and compared the values to those of GroES [1].
• The cDNA specifies a protein of 102 amino acids which, when transcribed and translated in vitro, yields a single basic product (pI > 9) that co-migrates exactly with the heat shock inducible cpn10 of rat hepatoma cells during 2D gel-electrophoresis [2].
• In the present study we report the occurrence of chaperonins, cpn10 and cpn60, in Chromatium vinosum and rat hepatocytes, using specific polyclonal antibodies in conjunction with the protein A-gold immunocytochemical technique [3].

High impact information on Hspe1

• Bacterial and mitochondrial cpn10 compete for a common saturable site on bacterial cpn60 [4].
• Mitochondria contain a polypeptide that is functionally equivalent to Escherichia coli chaperonin 10 (cpn10; also known as groES) [4].
• This mitochondrial cpn10 has been identified in beef and rat liver and is able to replace bacterial cpn10 in the chaperonin-dependent reconstitution of chemically denatured ribulose-1,5-bisphosphate carboxylase [4].
• To elucidate the structural features of this topogenic signal, peptides representing residues 1-25 of rat Cpn10 were synthesized with and without the naturally occurring N-terminal acetylation [5].
• Single bands for the cpn10 and cpn60 were also detected in pancreatic juice [6].

Biological context of Hspe1

• Three chaperones, the chaperonins cpn10 and cpn60, and the hsp70 protein, were revealed by immunochemistry and cytochemistry in pancreatic rat acinar cells [6].
• Recently, the sequence of mitochondrial chaperonin 10 from Rattus norvegicus (rat cpn10), with N-terminal acetylation, has been published [7].

Anatomical context of Hspe1

• Western immunoblotting analysis of rat pancreas homogenates has shown that antibodies against cpn10, cpn60 and hsp70 protein recognize single protein bands of 25 kDa, 60 kDa and 70 kDa, respectively [6].
• On the other hand, using the post-embedding immunoelectron microscopy technique cpn10 and cpn60 were localized specifically in liver mitochondria and peroxisomes [3].

Associations of Hspe1 with chemical compounds

• It is concluded that cpn10, unlike the majority of nuclear-encoded proteins of the mitochondrial matrix, is synthesised without a cleavable targeting signal and that, following removal of the initiating methionine, it becomes acetylated prior to mitochondrial import [2].
• Incubation of 3H- or 35S-labelled cpn10 with mitochondria confirms these conclusions and shows that cpn10 is imported into mitochondria in an energy-dependent process which is inhibited by the presence of 2,4-dinitrophenol [2].
• Thus, like the bacterial homologue, mitochondrial cpn10 facilitates a K(+)- and Mg.ATP-dependent discharge of unfolded (or partially folded) ribulose bisphosphate carboxylase from bacterial chaperonin 60 (cpn60; also known as groEL) [4].
• Two syntheses of rat cpn10 were performed, the first using a classical carbodiimide-mediated double coupling protocol (Method A) and the second a more efficient HBTU/HOBT/single coupling procedure (Method B) [7].
• Free rat cpn10 was released from avidin-agarose column with 5% aqueous triethylamine and after desalting by RP-HPLC gave 9.9% recovery [8].

Analytical, diagnostic and therapeutic context of Hspe1

• Immunofluorescence studies on rat pancreatic tissue revealed a strong positive signal in the apical region of the acinar cells for cpn10 and cpn60, while an immunoreaction was detected at the juxtanuclear Golgi region with the anti-hsp70 antibody [6].
• As demonstrated by quantitative evaluations, the immunolabeling for cpn10 and cpn60 in C vinosum cells was associated primarily with the bacterial cell envelope [3].

References