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Identification of the Major Postsynaptic Density Protein as Homologous with the Major Calmodulin‐Binding Subunit of a Calmodulin‐Dependent Protein Kinase
Author(s) -
Goldenring James R.,
McGuire Joseph S.,
DeLorenzo Robert J.
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb12713.x
Subject(s) - calmodulin , autophosphorylation , postsynaptic density , protein kinase a , protein subunit , biochemistry , biology , postsynaptic potential , binding protein , phosphorylation , microbiology and biotechnology , receptor , enzyme , gene
The major postsynaptic density protein (mPSDp), comprising >50% of postsynaptic density (PSD) protein, is an endogenous substrate for calmodulin‐dependent phosphorylation as well as a calmodulin‐binding protein in PSD preparations. The results in this investigation indicate that mPSDp is highly homologous with the major calmodulin‐binding subunit (p) of tubulin‐associated calmodulin‐dependent kinase (TACK), and that PSD fractions also contain a protein homologous with the o‐subunit of TACK. Homologies between mPSDp and a 63,000 dalton PSD protein and the p‐ and ó‐subunits of TACK were established by the following criteria: (1) identical apparent molecular weights: (2) identical calmodulin‐binding properties; (3) manifestation of Ca 2+ ‐calmodulin‐stimulated autophosphorylation; (4)identical isoelectric points; (5) identical calmodulin binding and autophosphorylation patterns on two‐dimensional gels; (6) homologous two‐dimensional tryptic peptide maps; and (7) similar phosphoamino acid‐specific phosphorylation of tubulin. The results suggest that mPSDp is a calmodulin‐binding protein involved in modulating protein kinase activity in the postsynaptic density and that a tubulin kinase system homologous with TACK exists in a membrane‐bound form in the PSD.