an excellent substrate for protein kinase C in intact 
cells, in contrast to the current view that substrates 
for this kinase need to be membrane-associated. He 
also found that the protein contained four serines 
phosphorylated by protein kinase C that were clus- 
tered in a 2 5 -amino acid basic domain, the phos- 
phorylation site domain. Synthetic peptides com- 
prising this domain were phosphorylated by 
protein kinase C with high affinity and positive 
cooperativity; a peptide in which all four serines 
were replaced by alanines behaved as a potent 
pseudosubstrate inhibitor for the kinase. 
Dr. Graff also found that the MARCKS protein 
could bind calmodulin and that this binding was 
prevented by prior phosphorylation of the protein 
by protein kinase C. This led to the finding that the 
phosphorylation site domain and the calmodulin- 
binding domain were contiguous or identical, a 
PUBLICATIONS 
prediction confirmed by the finding that the phos- 
phorylation site domain peptide could bind 
calmodulin with high affinity. The current hypothe- 
sis is that calmodulin and the MARCKS protein exist 
in cells as a complex under conditions of protein 
kinase C inactivity: when the kinase is activated (al- 
most always in situations in which cellular calcium 
concentrations are transiently elevated) the com- 
ponents of the complex separate; the "free" 
calmodulin could then act, in concert with the ele- 
vated calcium levels, to activate various calmodulin- 
activated enzymes. This might provide a mechanism 
for the synergistic interaction between the two 
pathways that has been noted. 
Dr. Blackshear is also Professor of Medicine and 
Assistant Professor of Biochemistry at Duke Univer- 
sity Medical Center. 
Books and Chapters of Books 
Blackshear, PJ. 1988. Carbohydrate metabolism. In Textbook of Internal Medicine (Kelley, WN., Jr., Ed.). Phil- 
adelphia: Lippincott, pp 2130-2133. 
Articles 
Blackshear, PJ. 1988. Approaches to the study of protein kinase C involvement in signal transduction. Am J 
Med Sci 296:251-240. 
Blackshear, PJ. 1989. Insulin-stimulated protein biosynthesis as a paradigm of protein kinase C-independent 
growth factor action. Clin Res 37:15-25. 
Blackshear, PJ., and Haupt, D.M. 1989. Evidence against insulin-stimulated phosphorylation of calmodulin in 
3T3-L1 adipocytes. J Biol Chem 264:3854-3858. 
Blackshear, PJ. , Manzella, J.M., Stumpo, D.J. , Wen, L., Huang, J.-Q., Oyen, O., and Young, S.W 1989. High 
level, cell-specific expression of ornithine decarboxylase transcripts in rat genitourinary tissues. Mol En- 
docrinol 3:68-78. 
Blackshear, PJ., Nairn, A.C., and Kuo, J.F. 1988. Protein kinases 1988: a current perspective. FASEB J 2:2957- 
2969. 
Blackshear, PJ., and Rohde, T.D. 1989. Implantable infusion pumps for drug delivery in man: theoretical and 
practical considerations. Horiz Biochem Biophys 9:293-309. 
Blackshear, PJ., Roussell, A.M., Cohen, A.M., and Nathan, D.M. 1989. Basal rate intravenous insulin infusions 
compared to conventional insulin treatment in patients with Type II diabetes. A prospective, crossover 
trial. Diabetes Care 12:455-463. 
Graff, J.M., Stumpo, D.J. , and Blackshear, PJ. 1989. Characterization of the phosphorylation sites in the 
chicken and bovine myristoylated alanine-rich C kinase substrate (MARCKS) protein, a prominent cellular 
substrate for protein kinase Q.J Biol Chem 264:11912-11919. 
Levenson, R.M., Nairn, A.C., and Blackshear, PJ. 1989. Insulin rapidly induces the biosynthesis of elongation 
factor-2. J Biol Chem 264:11904-11911. 
Stumpo, DJ. , Graff, J.M., Albert, K.A., Greengard, P, and Blackshear, PJ. 1989. Molecular cloning, character- 
ization, and expression of a cDNA encoding the "80- to 87-kDA" myristoylated alanine-rich C kinase sub- 
strate: a major cellular substrate for protein kinase C. Proc Natl Acad Sci USA 86:4012-4016. 
Continued 
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