June 1, 1989Annual Review of Biochemistry
The Structure and Regulation of Protein Phosphatases
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Discussion
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Implication
Biochemical review reveals how second messengers and targeting subunits control protein phosphatases in animal cells, highlighting mechanisms regulating metabolism and muscle contractility.
Key Points
- To review the structure, subcellular distribution, and regulatory mechanisms governing the four major serine/threonine-specific protein phosphatases in animal cells.
- Examined enzymatic properties and structures of cytoplasmic catalytic subunits PP-1, PP-2A, PP-2B, and PP-2C isolated from animal tissues.
- Assessed regulatory interactions involving targeting subunits, second messengers (calcium and cyclic AMP), and pharmacological inhibitors such as okadaic acid.
- PP-1, PP-2A, and PP-2B share gene family homology and form multi-subunit complexes in vivo, whereas PP-2C functions predominantly as an isolated monomeric enzyme.
- Active PP-1 is targeted to specific subcellular structures via specialized subunits—such as PP-1G on glycogen and PP-1M on myofibrils—which dictate localization and substrate specificity.
- Second messengers cyclic AMP and calcium regulate PP-1 and PP-2B through kinase-driven phosphorylation cascades, inhibitor-1 modulation, and allosteric control mechanisms.
Cite This Study
Philip Cohen (1989) studied this question.