Regulation of cAMP concentration by calmodulin-dependent cyclic nucleotide phosphodiesterase

1986 ◽  
Vol 64 (11) ◽  
pp. 1072-1080 ◽  
Author(s):  
Rajendra K. Sharma ◽  
Jerry H. Wang
Keyword(s):  
Protein Kinase ◽  
Cyclic Nucleotide ◽  
Bovine Brain ◽  
Cyclic Nucleotide Phosphodiesterase ◽  
Camp Concentration ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Molecular Masses ◽  
Regulatory Properties

Bovine brain contains two major calmodulin (CaM) dependent phosphodiesterase isozymes which are homodimeric proteins with subunit molecular masses of 60 and 63 kilodaltons (kDa), respectively. The 60-kDa subunit isozyme can be phosphorylated by cAMP-dependent protein kinase, resulting in a decrease in the enzyme affinity towards CaM. The phosphorylation is blocked by Ca2+ and CaM and reversed by the CaM-stimulated phosphatase (calcineurin). The 63-kDa subunit isozymes can also be phosphorylated, but in this case by a CaM-dependent protein kinase(s). This phosphorylation is also accompanied by a decrease in the isozyme affinity towards CaM and can be reversed by the CaM-dependent phosphatase. Analysis of the complex regulatory properties of the phosphodiesterase isozymes has led to the suggestion that fluxes of cAMP and Ca2+ during cell activations are closely coupled and that the CaM-dependent phosphodiesterase isozymes play key roles in this signal coupling phenomenon.

scholarly journals Regulation by light of cyclic nucleotide-dependent protein kinases and their substrates in frog rod outer segments.

1990 ◽  
Vol 95 (3) ◽  
pp. 545-567 ◽  
Author(s):  
H Hamm
Keyword(s):  
Protein Kinase ◽  
Cyclic Nucleotide ◽  
Soluble Fraction ◽  
Subcellular Fractionation ◽  
Rod Outer Segments ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Outer Segments ◽  
Dependent Protein ◽  
Membrane Bound

Cyclic nucleotides (both cAMP and cGMP) stimulate the phosphorylation of several proteins of 65-70, 50-52, 21, 13, and 12 kD in rod outer segments (ROS) of the frog retina. Subcellular fractionation showed that phosphopeptides of 67, 21, 13, and 12 kD were soluble and phosphopeptides of 69, 67, 50-52, and 12 kD were membrane associated at physiological ionic strength. Components I and II, 13 and 12 kD, respectively, are the major cyclic nucleotide-dependent phosphoproteins of ROS and have been reported to be phosphorylated in the dark and dephosphorylated in the light. Under unstimulated conditions, phosphorylated Components I and II were found in the soluble fraction. Cyclic nucleotide stimulation of phosphorylation resulted in increased phospho-Components I and II in the soluble fraction, and phospho-Component II on the membrane. Light had no effect on the phosphorylation level of soluble Components I and II, but it caused a depletion within 1 s of the membrane-bound phospho-Component II. A half-maximal decrease in membrane-bound Component II was seen at 5 x 10(5) rhodopsins bleached per outer segment. The cyclic nucleotide-dependent protein kinase(s) were found primarily in the peripheral membrane fraction of ROS proteins. 8-bromo cyclic AMP was two orders of magnitude more effective than 8-bromo cyclic GMP at stimulating Component I and II phosphorylation. An active peptide of the Walsh inhibitor of cAMP-dependent protein kinase [PKI(5-22)amide] blocked the phosphorylation with an IC50 of 10 nM. Photoaffinity labeling studies with 8-N3-cAMP and 8-N3-cGMP revealed the presence of a 52-kD band specifically labeled with 8-N3-cAMP, but no specific 8-N3-cGMP labeling. These data suggest that cyclic nucleotide-dependent protein phosphorylation in ROS occurs via the activation of a cAMP-dependent protein kinase.

scholarly journals Fast and Slow Cyclic Nucleotide-dissociation Sites in cAMP-dependent Protein Kinase Are Transposed in Type Iβ cGMP-dependent Protein Kinase

1996 ◽  
Vol 271 (29) ◽  
pp. 17570-17575 ◽  
Author(s):  
Robin B. Reed ◽  
Mårten Sandberg ◽  
Tore Jahnsen ◽  
Suzanne M. Lohmann ◽  
Sharron H. Francis ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Nucleotide ◽  
Dependent Protein Kinase ◽  
Cgmp Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein
Sign in / Sign up

Export Citation Format

Share Document