Intermediate-type 20 S Proteasomes in HeLa Cells: “Asymmetric” Subunit Composition, Diversity and Adaptation

Klare, Nicola; Seeger, Michael; Janek, Katharina; Jungblut, Peter R.; Dahlmann, Burkhardt

doi:10.1016/j.jmb.2007.07.038

Cited by 107 publications

(90 citation statements)

References 53 publications

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“…As described above, 20S proteasomes can contain standard-or immuno-subunits or a mixture of both and thus exist as standard-immuno-and intermediateproteasomes, respectively. Each subpopulation exhibits a different pattern of chymotryptic, tryptic and caspaselike activity and they also differ in their activity towards the 25mer polypeptide pp89 (Dahlmann et al 2000;Klare et al 2007). Therefore, we studied whether there exist age-dependent alterations in the subunit composition of rat liver proteasomes that might explain the partial loss of the measured caspase-like activity.…”

Section: Separation Of 20s Proteasome Into Subpopulationsmentioning

confidence: 99%

“…This phenomenon most likely results from the significant loss of subpopulations ΙΙ and ΙΙΙ as well as from the transition of intermediate-type proteasomes to immuno-proteasomes that exhibit lower caspase-like activity than standard and intermediate-type proteasomes (Dahlmann et al 2000;Klare et al 2007;Kloss et al 2009). Fig.…”

Section: Peptide Hydrolysing Activity Of Proteasome Subpopulationsmentioning

confidence: 99%

“…Thus, irrespective of whether they are present as complexes of 26S/30S or any other form of proteasome in the cell, 20S proteasomes exist in two major forms designated standard-and immuno-proteasomes, which exhibit the three proteolytic activities to different extents (Gaczynska et al 1994;Ustrell et al 1995;Boes et al 1994). An incomplete replacement of standard-subunits by immuno-subunits results in the formation of a third population designated intermediate-type proteasomes, which can be further subdivided into subpopulations according to the extent of standard by immuno-subunit replacement (Klare et al 2007;Dahlmann et al 2000;Guillaume et al 2010). We have shown previously that proteasomes of rat liver all comprised intermediate-type subunit compositions (Dahlmann et al 2000;Schmidt et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Molecular alterations in proteasomes of rat liver during aging result in altered proteolytic activities

Gohlke

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Textoris-Taube

et al. 2013

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Aging induces alterations of tissue protein homoeostasis. To investigate one of the major systems catalysing intracellular protein degradation we have purified 20S proteasomes from rat liver of young (2 months) and aged (23 months) animals and separated them into three subpopulations containing different types of intermediate proteasomes with standard-and immunosubunits. The smallest subpopulation ΙΙΙ and the major subpopulation Ι comprised proteasomes containing immuno-subunits β1i and β5i beside small amounts of standard-subunits, whereas proteasomes of subpopulation ΙΙ contained only β5i beside standard-subunits. In favour of a relative increase of the major subpopulation Ι, subpopulation ΙΙ and ΙΙΙ were reduced for about 55 % and 80 %, respectively, in aged rats. Furthermore, in all three 20S proteasome subpopulations from aged animals standard-active site subunits were replaced by immunosubunits. Overall, this transformation resulted in a relative increase of immuno-subunit-containing proteasomes, paralleled by reduced activity towards short fluorogenic peptide substrates. However, depending on the substrate their hydrolysing activity of long polypeptide substrates was significantly higher or unchanged. Furthermore, our data revealed an altered MHC class I antigen-processing efficiency of 20S proteasomes from liver of aged rats. We therefore suggest that the age-related intramolecular alteration of hepatic proteasomes modifies its cleavage preferences without a general decrease of its activity. Such modifications could have implications on protein homeostasis as well as on MHC class I antigen presentation as part of the immunosenescence process.

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Section: Separation Of 20s Proteasome Into Subpopulationsmentioning

confidence: 99%

Section: Peptide Hydrolysing Activity Of Proteasome Subpopulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular alterations in proteasomes of rat liver during aging result in altered proteolytic activities

Gohlke

Mishto

Textoris-Taube

et al. 2013

AGE

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“…As revealed by PISA analysis, the number of interaction sites between adjacent subunits of the cCP and the iCP differ (Table 15), but the impact on the stability or half-life of the CPs cannot be predicted from the structural data. However, the subunit interaction surfaces of the proteolytically active subunits and their adjacent neighbours enable the formation of mixed proteasome species, which were previously suggested to be physiologically relevant [29][30] . [32] .…”

Section: Subunit Architecture Of the Ccp And Icpmentioning

confidence: 99%

“…Furthermore, PA28αβ has been suggested to target iCPs to the TAP in the ER membrane in order to directly translocate the generated peptides into the ER lumen [28] . Besides the cCP and iCP, mixed proteasomes bearing the subunit composition β1c, β2c and β5i or β1c, β2i and β5i were reported to account for 30-50 % of all cellular CPs [29] and even CPs with asymmetric composition of β subunits were described [30] .…”

Section: Figure 2 Evolution Of 20s Proteasomes (A)mentioning

confidence: 99%

Structural and Functional Characterization of the Immunoproteasome

Huber¹

2013

Springer Theses

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Elucidating the Catalytic Subunit Composition of Distinct Proteasome Subtypes: A Crosslinking Approach Employing Bifunctional Activity‐Based Probes

et al. 2014

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In addition to two well-recognized proteasome subtypes—constitutive proteasomes and immunoproteasomes—mounting evidence also suggests the existence of intermediate proteasome subtypes containing unconventional mixtures of catalytic subunits. While they appear to play unique biological roles, the lack of practical methods for detecting distinct proteasome subtypes has limited functional investigations. Here, we report the development of activity-based probes that crosslink two catalytic subunits within intact proteasome complexes. Identification of the crosslinked subunit pairs provides direct evidence on the catalytic subunit composition of proteasomes. Using these probes, we found that U266 multiple myeloma cells contain intermediate proteasomes comprising both β1i and β2, but not β1 and β2i, consistent with previous findings with other cell types. Our bifunctional probes can be utilized in functional investigations of distinct proteasome subtypes in various biological settings.

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Intermediate-type 20 S Proteasomes in HeLa Cells: “Asymmetric” Subunit Composition, Diversity and Adaptation

Cited by 107 publications

References 53 publications

Molecular alterations in proteasomes of rat liver during aging result in altered proteolytic activities

Molecular alterations in proteasomes of rat liver during aging result in altered proteolytic activities

Structural and Functional Characterization of the Immunoproteasome

Elucidating the Catalytic Subunit Composition of Distinct Proteasome Subtypes: A Crosslinking Approach Employing Bifunctional Activity‐Based Probes

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