Two protein phosphatase 2A (PP2A) holoenzymes were isolated from rabbit skeletal muscle containing, in addition to the catalytic and PR65 regulatory subunits, proteins of apparent molecular masses of 61 and 56 kDa respectively. Both holoenzymes displayed low basal phosphorylase phosphatase activity, which could be stimulated by protamine to an extent similar to that of previously characterized PP2A holoenzymes. Protein microsequencing of tryptic peptides derived from the 61 kDa protein, termed PR61, yielded 117 residues of amino acid sequence. Molecular cloning by enrichment of specific mRNAs, followed by reverse transcription–PCR and cDNA library screening, revealed that this protein exists in multiple isoforms encoded by at least three genes, one of which gives rise to several splicing variants. Comparisons of these sequences with the available databases identified one more human gene and predicted another based on a rabbit cDNA-derived sequence, thus bringing the number of genes encoding PR61 family members to five. Peptide sequences derived from PR61 corresponded to the deduced amino acid sequences of either α or β isoforms, indicating that the purified PP2A preparation was a mixture of at least two trimers. In contrast, the 56 kDa subunit (termed PR56) seems to correspond to the ϵ isoform of PR61. Several regulatory subunits of PP2A belonging to the PR61 family contain consensus sequences for nuclear localization and might therefore target PP2A to nuclear substrates.
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July 1996
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Research Article|
July 01 1996
The variable subunit associated with protein phosphatase 2A0 defines a novel multimember family of regulatory subunits
Stanislaw ZOLNIEROWICZ;
Stanislaw ZOLNIEROWICZ
‡
*Friedrich Miescher-Institut, P.O. Box 2543, CH-4002 Basel, Switzerland
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Christine VAN HOOF;
Christine VAN HOOF
†Afdeling Biochemie, Faculteit der Geneeskunde, Katholieke Universiteit te Leuven, Herestraat 49, 3000 Leuven, Belgium
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Nataša ANDJELKOVIĆ;
Nataša ANDJELKOVIĆ
*Friedrich Miescher-Institut, P.O. Box 2543, CH-4002 Basel, Switzerland
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Peter CRON;
Peter CRON
*Friedrich Miescher-Institut, P.O. Box 2543, CH-4002 Basel, Switzerland
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Ilse STEVENS;
Ilse STEVENS
†Afdeling Biochemie, Faculteit der Geneeskunde, Katholieke Universiteit te Leuven, Herestraat 49, 3000 Leuven, Belgium
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Wilfried MERLEVEDE;
Wilfried MERLEVEDE
†Afdeling Biochemie, Faculteit der Geneeskunde, Katholieke Universiteit te Leuven, Herestraat 49, 3000 Leuven, Belgium
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Jozef GORIS;
Jozef GORIS
†Afdeling Biochemie, Faculteit der Geneeskunde, Katholieke Universiteit te Leuven, Herestraat 49, 3000 Leuven, Belgium
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Brian A. HEMMINGS
Brian A. HEMMINGS
§
§To whom correspondence should be addressed.
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Publisher: Portland Press Ltd
Received:
December 15 1995
Revision Received:
January 31 1996
Accepted:
February 27 1996
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 317 (1): 187–194.
Article history
Received:
December 15 1995
Revision Received:
January 31 1996
Accepted:
February 27 1996
Citation
Stanislaw ZOLNIEROWICZ, Christine VAN HOOF, Nataša ANDJELKOVIĆ, Peter CRON, Ilse STEVENS, Wilfried MERLEVEDE, Jozef GORIS, Brian A. HEMMINGS; The variable subunit associated with protein phosphatase 2A0 defines a novel multimember family of regulatory subunits. Biochem J 1 July 1996; 317 (1): 187–194. doi: https://doi.org/10.1042/bj3170187
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