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P M Kloetzel

Publications and source records attributed to P M Kloetzel.

92 records · Page 6Linked to original sources
PubMedDate not supplied

The effect of heat shock on 20S/26S proteasomes.

We have studied the consequences of heat shock on 20S/26S proteasome activity and activation, the proteasomal subunit composition, proteasome assembly, subunit mRNA stability as well as on the intracellular distribution of proteasomes. Our data show that heat shock locks 20S proteasomes in their latent inactive state and impairs further activation of the 26S proteasome by ATP. Proteasome mRNA levels are decreased after heat shock and the assembly of the proteasome complex is inhibited. Heat shock also induces a rapid reorganisation of the cellular distribution of the proteasome which appears to be connected with proteasome activity and the change of the cellular architecture after heat shock.

Adenosine Triphosphate↗
PubMedDate not supplied

Phosphoamino acids in proteasome subunits.

Proteasomes, the major catalysts of the non-lysosomal proteolytic pathway in eukaryotic cells, were analyzed for their content of phosphoamino acids using polyacrylamide gel electrophoresis and subsequent detection on Western blots by phosphoamino acid antibodies. No specific binding to proteasome subunits was observed with phosphoserine or phosphothreonine antibodies, whereas phosphotyrosine antibodies were bound by a single proteasome subunit, which was identified in rat as well as in human proteasomes as subunit C7-1. Since dephosphorylation of the subunit by phosphatases was not possible, analysis of phosphoamino acid content of all proteasome subunits was performed using another method. All proteasome subunits were isolated from 2D-polyacrylamide gels and subjected to partial acid hydrolysis. Phosphoamino acids were subsequently detected by capillary electrophoresis after their derivatization with phenylisothiocyanate. This analysis revealed no phosphorylated amino acid in subunit C7-1, however, subunit C3 contained phosphotyrosine and phosphothreonine, and phosphoserine was detected in subunits zeta, C5, C8 and C9.

Amino Acids↗