Mutual protection of microtubule-associated protein 2 (MAP2) and cyclic AMP-dependent protein kinase II against μ-calpain
✍ Scribed by A. Alexa; P. Tompa; A. Baki; G. Vereb; P. Friedrich
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 807 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0360-4012
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✦ Synopsis
Phosphorylation by adenosine-3' ,5'-cyclic monophosphate (CAMP)-dependent protein kinase (PKA), but not by Ca+ + -calmodulin-dependent protein kinase I1 (CaMK 11), was shown earlier to protect microtubule-associated protein 2 (MAP2) from cleavage by m-calpain (Johnson and Foley: J Neurosci Res 34: 642-647, 1993). We reinvestigated this phenomenon with the physiologically more relevant p-calpain and found a qualitatively similar but quantitatively different picture. We further demonstrate that 1) protection is biphasically dependent on the degree of phosphorylation; 2) Ca + + -phospholipid-dependent protein kinase (PKC) has about the same effect as PKA; 3) the effects of kinases A and C are not additive; and 4) stripping of native MAP2 from its phosphate content (17.8 -I 2.3 mol/mol) enhances calpainolysis 3.6-fold.
A reciprocal effect between kinase A and MAP2 was found: the RII, but not the RI, regulatory subunit of kinase A, which was shown to bind specifically to MAP2, is protected by MAP2 from p-calpain attack. It is suggested that the specific anchoring of kinase A-I1 on MAP2 may serve not only kinase targeting in the dendrites, but also protection from calpainolytic degradation.