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A monoclonal antibody that distinguishes latent and active forms of the proteasome (multicatalytic proteinase complex)Monoclonal antibodies (mAbs) were generated to proteasome purified from human erythrocytes. Five of six proteasome-specific mAbs reacted with three subunits in the molecular mass range of 25-28 kDa, indicating a common epitope. The other mAb (AP5C10) exhibited a more restricted reactivity, recognizing a 32-kDa subunit of the proteasome purified in its latent state. However, when the proteasome is isolated in its active state, AP5C10 reacts with a 28-kDa subunit, evidence for processing of the proteasome subunits during purification. Purified proteasome preparations which exhibited partial latency have both AP5C10 reactive subunits. Although the 32-kDa subunit appears required for latency, loss of this component and generation of the 28-kDa component are not obligatory for activation. The 32- and 28-kDa subunits can each be further resolved into three components by isoelectric focusing. The apparent loss of 4 kDa during the conversion of the 32- to 28-kDa subunit is accompanied by a shift to a more basic pI for each polypeptide. Western blots of the early steps of proteasome purification reveal an AP5C10-reactive protein at 41 kDa. This protein was separated from proteasomes by sizing chromatography and may represent a pool of precursor subunits. Since the 32-kDa subunit appears necessary for latency, it is speculated to play a regulatory role in ATP-dependent proteolytic activity.
Document ID
Document Type
Reprint (Version printed in journal)
Weitman, D. (New York Medical College Valhalla 10595)
Etlinger, J. D.
Date Acquired
August 22, 2013
Publication Date
April 5, 1992
Publication Information
Publication: The Journal of biological chemistry
Volume: 267
Issue: 10
ISSN: 0021-9258
Subject Category
Life Sciences (General)
Funding Number(s)
Distribution Limits
NASA Discipline Musculoskeletal
Non-NASA Center