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Protein kinase C-mediated phosphorylation and calmodulin binding of recombinant myristoylated alanine-rich C kinase substrate (MARCKS) and MARCKS-related protein
The myristoylated alanine-rich C kinase substrate (MARCKS) and the MARCKS-related protein (MRP) are members of a distinct family of protein kinase C (PKC) substrates that also bind calmodulin in a manner regulated by phosphorylation by PKC. The kinetics of PKC-mediated phosphorylation and the calmod...
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Published in: | The Journal of biological chemistry 1994-03, Vol.269 (12), p.9361-9367 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The myristoylated alanine-rich C kinase substrate (MARCKS) and the MARCKS-related protein (MRP) are members of a distinct
family of protein kinase C (PKC) substrates that also bind calmodulin in a manner regulated by phosphorylation by PKC. The
kinetics of PKC-mediated phosphorylation and the calmodulin binding properties of intact, recombinant MARCKS and MRP were
investigated and compared with previous studies of synthetic peptides spanning the PKC phosphorylation site/calmodulin binding
domains (PSCBD) of these proteins. Both MARCKS and MRP were high affinity substrates for the catalytic fragment of PKC, and
their phosphorylation occurred with positive cooperativity (MARCKS: S0.5 = 100 nM, KH = 1.43; MRP: S0.5 = 238 nM, KH = 1.72).
These affinities are similar to the values determined from studies of their respective PSCBD peptides. Two-dimensional mapping
of MRP and its synthetic PSCBD peptide yielded identical patterns of tryptic phosphopeptides, indicating that, as in the case
of MARCKS, all of the PKC phosphorylation sites in MRP lie within the 24-amino acid PSCBD. Sequence analysis of tryptic phosphopeptides
revealed that the first and third, but not the second, serines in the MRP PSCBD were phosphorylated by PKC. Both MARCKS and
MRP bound dansyl-calmodulin with high affinity, with a Kapp of 4.6 and 9.5 nM, respectively. Phosphorylation of MARCKS and
MRP by PKC disrupted the protein-calmodulin complexes, with half-lives of 4.0 and 3.5 min, respectively. These studies suggest
that intact, recombinant MARCKS and MRP are accurately modeled by their synthetic PSCBD peptides with respect to PKC phosphorylation
kinetics and their phosphorylation-dependent calmodulin binding properties. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)37116-8 |