Involvement of the 10-kDa C-terminal fragment of hsc70 in complexing with unfolded protein.
Using native gel electrophoresis, we demonstrate that both bovine brain hsc70 and recombinant rat hsc70 form a tightly associated complex with bovine S-carboxymethyl alpha-lactalbumin (CMLA). The formation of the complexes can be inhibited by an octapeptide (KLALSLHD). The recombinant C-terminal 30-kDa fragment also can be tightly associated with CMLA. Consequently, the 44-kDa ATPase domain of hsc70 plays a small role in the formation of the hsc70/CMLA. The N-terminal 60-kDa fragment of hsc70 cannot form a similar complex, despite the finding that the hydrolysis of ATP both by hsc70 and by the 60-kDa fragment can be stimulated by CMLA in a similar concentration-dependent manner with EC50 values of 15 microM. Moreover, the C-terminal 10-kDa fragment of hsc70 cannot tightly associate with CMLA, indicating that this fragment is necessary but not sufficient for the formation of the hsc70/CMLA complex.
Hu
S M
SM
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China.
Wang
C
C
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D017931:DNA Primers / Q000235:genetics; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D066298:In Vitro Techniques; D007768:Lactalbumin / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; D017931:DNA Primers; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C494373:Hspa8 protein, rat; D046911:Macromolecular Substances; D010446:Peptide Fragments; D011994:Recombinant Proteins; D007768:Lactalbumin; D000251:Adenosine Triphosphatases