The long term goal of this project is to characterize the structure and function of P-57, a novel calmodulin (CaM) binding protein from brain. We have recently purified P-57 to apparent homogeneity from bovine cerebral cortex membranes. In contrast to other CaM binding proteins, P-57 apparently has higher affinity for CaM in the absence of bound Ca2+ than in its presence and Ca2+ causes the release of CaM from P-57. It is hypothesized that P-57 may function to bind CaM at some local site within the cell and release CaM in response to increases in free Ca2+.
The specific aims of this project include quantitation of binding between P-57 and CaM in the presence and absence of Ca2+, determining if P-57 interacts with other polypeptides in brain, examination of the tissue distribution of P-57, characterization of the physical properties of P-57, characterization of cAMP dependent protein kinase catalyzed phosphorylation of P-57, and determination of the influence of phosphorylation on the affinity of P-57 for CaM. Homogeneous P-57 in mg quantities, anti-P57 rabbit polyclonal antibodies, and fluorescent labeled CaM derivatives are currently available for the proposed experiments.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Biochemistry Study Section (BIO)
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University of Washington
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Liu, Y; Fisher, D A; Storm, D R (1994) Intracellular sorting of neuromodulin (GAP-43) mutants modified in the membrane targeting domain. J Neurosci 14:5807-17
Liu, Y; Fisher, D A; Storm, D R (1993) Analysis of the palmitoylation and membrane targeting domain of neuromodulin (GAP-43) by site-specific mutagenesis. Biochemistry 32:10714-9
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Liu, Y C; Storm, D R (1991) Expression of a neuromodulin-beta-galactosidase fusion protein in primary cultured neurons and its accumulation in growth cones. Mol Cell Biochem 104:29-34
Apel, E D; Byford, M F; Au, D et al. (1990) Identification of the protein kinase C phosphorylation site in neuromodulin. Biochemistry 29:2330-5

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