Calcium-Dependent and -Independent Interactions of the Calmodulin-Binding Domain of Cyclic Nucleotide Phosphodiesterase with Calmodulin†

Biochemistry ◽  
1999 ◽  
Vol 38 (5) ◽  
pp. 1446-1455 ◽  
Author(s):  
Tao Yuan ◽  
Michael P. Walsh ◽  
Cindy Sutherland ◽  
Heinz Fabian ◽  
Hans J. Vogel
Keyword(s):  
Cyclic Nucleotide ◽  
Binding Domain ◽  
Cyclic Nucleotide Phosphodiesterase ◽  
Calcium Dependent ◽  
Calmodulin Binding

Calmodulin-binding peptides isolated from α-casein peptone

1995 ◽  
Vol 62 (4) ◽  
pp. 587-592 ◽  
Author(s):  
Kenji Kizavva ◽  
Keiko Naganuma ◽  
Umeji Murakami
Keyword(s):  
Enzyme Activity ◽  
Cyclic Nucleotide ◽  
Cyclic Nucleotide Phosphodiesterase ◽  
Phosphodiesterase Activity ◽  
Calmodulin Binding ◽  
C Terminus ◽  
Binding Peptides

SUMMARYPeptides that inhibit calmodulin-dependent cyclic nucleotide phosphodiesterase were isolated from a pepsin digest of α-casein. Analysis of these peptides showed that they corresponded to the αs2-casein sequences 164–179 (Leu–Lys–Lys–Ile–Ser–Gln–Arg–Tyr–Gln–Lys–Phe–Ala–Leu–Pro–Gln–Tyr), 183–206 (Val–Tyr–Gln–His–Gln–Lys–Ala–Met–Lys–Pro–Trp–Ile–Gln–Pro–Lys–Thr–Lys–Val–Ile–Pro–Tyr–Val–Arg–Tyr) and 183–207 (C-terminus, Val–Tyr–Gln–His–Gln–Lys–Ala–Met–Lys–Pro–Trp–Ile–Gln–Pro–Lys–Thr–Lys–Val–Ile–Pro–Tyr–Val–Arg–Tyr–Leu). These peptides inhibited calmodulin-induced cyclic nucleotide phosphodiesterase activity over the range 1–50 μM without affecting the basal enzyme activity. These results demonstrated that the affinities of these peptides for calmodulin are comparable to the affinities of certain endogenous neurohormones and proteins that interact with calmodulin.

scholarly journals KS-505a, an isoform-selective inhibitor of calmodulin-dependent cyclic nucleotide phosphodiesterase

1996 ◽  
Vol 316 (1) ◽  
pp. 311-316 ◽  
Author(s):  
Michio ICHIMURA ◽  
Rika EIKI ◽  
Keiko OSAWA ◽  
Satoshi NAKANISHI ◽  
Hiroshi KASE
Keyword(s):  
Cyclic Nucleotide ◽  
Hippocampal Slices ◽  
Selective Inhibitor ◽  
Binding Domain ◽  
Cyclic Nucleotide Phosphodiesterase ◽  
Intracellular Camp ◽  
Camp Concentration ◽  
Striatal Slices

The effects of KS-505a, a novel microbial metabolite, on the activity of calmodulin-dependent cyclic nucleotide phosphodiesterase (CaM-PDE) were investigated. (1) KS-505a potently inhibited the purified 61 kDa isoenzyme of CaM-PDE from bovine brain and required much higher doses to inhibit the purified 59 kDa isoenzyme of CaM-PDE from bovine heart. The inhibition of both isoenzymes was observed only in the presence of calcium-activated calmodulin (Ca2+/CaM). The IC50 values for the 61 and 59 kDa isoenzymes were 0.17 and 13 μM respectively with 20 μM cAMP as a substrate. (2) Kinetic analysis indicated that the inhibitory mode of KS-505a for the 61 kDa isoenzyme was competitive with respect to Ca2+/CaM; the Ki for KS-505a was 0.089 μM. The inhibition was not competitive with respect to the substrates cAMP or cGMP. (3) KS-505a did not interfere with the interaction between Ca2+/CaM and n-phenyl-1-naphthylamine, a hydrophobic fluorescent probe, nor was it adsorbed to CaM-conjugated gels in the presence of Ca2+, thereby indicating that KS-505a does not bind to Ca2+/CaM. (4) Trypsin-activated 61 kDa isoenzyme, which lacked the Ca2+/CaM-binding domain, was not inhibited by KS-505a at less than micromolar concentrations. Taken together, these results suggest that KS-505a apparently bound to a site in the Ca2+/CaM-binding domain of the 61 kDa isoenzyme and selectively inhibited Ca2+/CaM-activated 61 kDa isoenzyme activity. (5) In rat hippocampal slices, KS-505a at 10 μM increased the intracellular cAMP concentration to approximately three times the basal level, whereas in rat striatal slices it had no effect on the cAMP concentration at concentrations of 1.0–10 μM, suggesting that each CaM-PDE isoenzyme functions differentially in these regions. These results demonstrate that KS-505a is a highly potent selective inhibitor both in vitro and in vivo and distinguishes between subfamily members within the CaM-PDE family.

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