Since their discovery about a decade ago, human Hap46/BAG-1M, the larger isoform Hap50/BAG-1L, and related structures have caused quite some astonishment because of the seemingly unlimited array of possible interaction partners belonging to completely unrelated protein families. This problem was partially resolved when it was realized that molecular chaperones of the heat shock protein family Hsp70 are major primary association partners, which in turn, are able to bind a wide variety of unrelated protein structures, thus forming ternary complexes. Moreover, the protein folding activity of Hsp70 chaperones is affected; hence, the designation "cochaperones." Although many different proteins require mediation by Hsp70 chaperones for interactions with Hap50/BAG-1L, Hap46/BAG-1M, and isoforms, several other partner proteins are able to associate directly. In addition, Hap46/BAG-1M and Hap50/BAG-1L are also able to interact with DNA by making use of a positively charged region close to the amino terminal end of the polypeptide chain. This is the molecular basis for their effects on transcriptional activities, which are emphasized in this review and for which a molecular model is presented.
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| http://dx.doi.org/10.1379/1466-1268(2006)11[295:aotcba]2.0.co;2 | DOI Listing |
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Multiple, but concerted cellular activities of the human protein Hap46/BAG-1M and isoforms.
Int J Mol Sci
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Biochemie-Zentrum der Universität Heidelberg, INF 328, D-69120 Heidelberg, Germany.
The closely related human and murine proteins Hap46/BAG-1M and BAG-1, respectively, were discovered more than a decade ago by molecular cloning techniques. These and the larger isoform Hap50/BAG-1L, as well as shorter isoforms, have the ability to interact with a seemingly unlimited array of proteins of completely unrelated structures. This problem was partially resolved when it was realized that molecular chaperones of the hsp70 heat shock protein family are major primary association partners, binding being mediated by the carboxy terminal BAG-domain and the ATP-binding domain of hsp70 chaperones.
View Article and Find Full Text PDFActivities of the cochaperones Hap46/BAG-1M and Hap50/BAG-1L and isoforms.
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March 2007
Universität Heidelberg, Percent Molekulare Evolution and Genomik, Im Neuenheimer Feld 230, D-69120 Heidelberg.
Since their discovery about a decade ago, human Hap46/BAG-1M, the larger isoform Hap50/BAG-1L, and related structures have caused quite some astonishment because of the seemingly unlimited array of possible interaction partners belonging to completely unrelated protein families. This problem was partially resolved when it was realized that molecular chaperones of the heat shock protein family Hsp70 are major primary association partners, which in turn, are able to bind a wide variety of unrelated protein structures, thus forming ternary complexes. Moreover, the protein folding activity of Hsp70 chaperones is affected; hence, the designation "cochaperones.
View Article and Find Full Text PDFMultiple biological activities of the mammalian protein Hap46/BAG-1.
Arzneimittelforschung
September 2005
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One of the most prominent features of the mammalian protein Hap46/BAG-1M and its isoforms is the ability to form complexes with an enormous variety of unrelated proteins. In the majority of these interactions, however, molecular chaperones of the hsp70 heat shock protein family are the primary interaction partners which themselves are able to bind very different protein structures by making use of their respective substrate-binding domains. The carboxy terminal portion of Hap46/BAG-1M and its isoforms, called the BAG domain, interacts with the adenosine triphosphate (ATP)-binding domain of hsp70 chaperones and thereby affects their protein folding activities.
View Article and Find Full Text PDFBiological activities of HAP46/BAG-1. The HAP46/BAG-1 protein: regulator of HSP70 chaperones, DNA-binding protein and stimulator of transcription.
EMBO Rep
February 2004
Universität Heidelberg, c/o Molekulare Evolution und Genomik, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany.
HAP46/BAG-1M and its isoforms affect the protein-folding activities of mammalian HSP70 chaperones. They interact with the ATP-binding domain of HSP70 or HSC70, leaving the substrate-binding site available for further interactions. Trimeric complexes can therefore form with, for example, transcription factors.
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