scholarly journals Localization of catalytic and regulatory subunits of cyclic AMP-dependent protein kinases in mitochondria from various rat tissues

1990 ◽  
Vol 270 (1) ◽  
pp. 181-188 ◽  
Author(s):  
G Schwoch ◽  
B Trinczek ◽  
C Bode
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinases ◽  
Type I ◽  
Matrix Space ◽  
Dependent Protein Kinase ◽  
Inner Membrane ◽  
Regulatory Subunits ◽  
C Subunit ◽  
Dependent Protein

Observation and quantification of the catalytic subunit C of cyclic AMP-dependent protein kinases by immuno-gold electron microscopy suggested a high concentration of cyclic AMP-dependent protein kinases in mitochondria from liver, kidney, heart and skeletal muscle, pancreas, parotid gland and brain cells. The position of gold particles pointed to a localization in the inner membrane/matrix space. A similar distribution was obtained by immunolocalization of the cyclic AMP-dependent protein kinase regulatory subunits RI and RII in liver, pancreas and heart cells. The results indicated the presence of both the type I and the type II cyclic AMP-dependent protein kinases in mitochondria of hepatocytes, and the preferential occurrence of the type I protein kinase in mitochondria from exocrine pancreas and heart muscle. The immunocytochemical results were confirmed by immunochemical determination of cyclic AMP-dependent protein kinase subunits in fractionated tissues. Determinations by e.l.i.s.a. of the C-subunit in parotid gland cell fractions indicated about a 4-fold higher concentration of C-subunit in the mitochondria than in a crude 1200 g supernatant. Immunoblot analysis of subfractions from liver mitochondria supported the localization in situ of cyclic AMP-dependent protein kinases in the inner membrane/matrix space and suggested that the type I enzyme is anchored by its regulatory subunit to the inner membrane. In accordance with the immunoblot data, the specific activity of cyclic AMP-dependent protein kinase measured in the matrix fraction was about twice that measured in whole mitochondria. These findings indicate the importance of cyclic AMP-dependent protein kinases in the regulation of mitochondrial functions.

scholarly journals Characterization of the protein kinase activities of human platelet supernatant and particulate fractions

1984 ◽  
Vol 218 (2) ◽  
pp. 285-294 ◽  
Author(s):  
S E Salama ◽  
R J Haslam
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Soluble Fraction ◽  
Deae Cellulose ◽  
Type I ◽  
Type Ii ◽  
Dependent Protein Kinase ◽  
Regulatory Subunits ◽  
Dependent Protein ◽  
Triton X

After human platelets were lysed by freezing and thawing in the presence of EDTA, about 35% of the total cyclic AMP-dependent protein kinase activity was specifically associated with the particulate fraction. In contrast, Ca2+-activated phospholipid-dependent protein kinase was found exclusively in the soluble fraction. Photoaffinity labelling of the regulatory subunits of cyclic AMP-dependent protein kinase with 8-azido-cyclic [32P]AMP indicated that platelet lysate contained a 4-fold excess of 49 000-Da RI subunits over 55 000-Da RII subunits. The RI and RII subunits were found almost entirely in the particulate and soluble fractions respectively. Chromatography of the soluble fraction on DEAE-cellulose demonstrated a single peak of cyclic AMP-dependent activity with the elution characteristics and regulatory subunits characteristic of the type-II enzyme. A major enzyme peak containing Ca2+-activated phospholipid-dependent protein kinase was eluted before the type-II enzyme, but no type-I cyclic AMP-dependent activity was normally observed in the soluble fraction. The particulate cyclic AMP-dependent protein kinase and associated RI subunits were solubilized by buffers containing 0.1 or 0.5% (w/v) Triton X-100, but not by extraction with 0.5 M-NaCl, indicating that this enzyme is firmly membrane-bound, either as an integral membrane protein or via an anchor protein. DEAE-cellulose chromatography of the Triton X-100 extracts demonstrated the presence of both type-I cyclic AMP-dependent holoenzyme and free RI subunits. These results show that platelets contain three main protein kinase activities detectable with histone substrates, namely a membrane-bound type-I cyclic AMP-dependent enzyme, a soluble type-II cyclic AMP-dependent enzyme and Ca2+-activated phospholipid-dependent protein kinase, which was soluble in lysates containing EDTA.

Association of catalytic and regulatory subunits of cyclic AMP-dependent protein kinase requires a negatively charged side group at a conserved threonine

1990 ◽  
Vol 10 (3) ◽  
pp. 1066-1075
Author(s):  
L R Levin ◽  
M J Zoller
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Yeast Cells ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Regulatory Subunits ◽  
C Subunit ◽  
Dependent Protein ◽  
Tight Association

In Saccharomyces cerevisiae, as in higher eucaryotes, cyclic AMP (cAMP)-dependent protein kinase is a tetramer composed of two catalytic (C) subunits and two regulatory (R) subunits. In the absence of cAMP, the phosphotransferase activity of the C subunit is inhibited by the tight association with R. Mutation of Thr-241 to Ala in the C1 subunit of S. cerevisiae reduces the affinity of this subunit for the R subunit approximately 30-fold and results in a monomeric cAMP-independent C subunit. The analogous residue in the mammalian C subunit is known to be phosphorylated. Peptide maps of in vivo 32P-labeled wild-type C1 and mutant C1(Ala241) suggest that Thr-241 is phosphorylated in yeast cells. Substituting Thr-241 with either aspartate or glutamate partially restored affinity for the R subunit. Uncharged and positively charged residues substituted at this site resulted in C subunits that failed to associate with the R subunit. Replacement with the phosphorylatable residue serine resulted in a C subunit with wild-type affinity for the R subunit. Analysis of this protein revealed that it appears to be phosphorylated on Ser-241 in vivo. These data suggest that the interaction between R and C involves a negatively charged phosphothreonine at position 241 of yeast C1, which can be mimicked by either aspartate, glutamate, or phosphoserine.

scholarly journals Association of catalytic and regulatory subunits of cyclic AMP-dependent protein kinase requires a negatively charged side group at a conserved threonine.

1990 ◽  
Vol 10 (3) ◽  
pp. 1066-1075 ◽  
Author(s):  
L R Levin ◽  
M J Zoller
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Yeast Cells ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Regulatory Subunits ◽  
C Subunit ◽  
Dependent Protein ◽  
Tight Association

In Saccharomyces cerevisiae, as in higher eucaryotes, cyclic AMP (cAMP)-dependent protein kinase is a tetramer composed of two catalytic (C) subunits and two regulatory (R) subunits. In the absence of cAMP, the phosphotransferase activity of the C subunit is inhibited by the tight association with R. Mutation of Thr-241 to Ala in the C1 subunit of S. cerevisiae reduces the affinity of this subunit for the R subunit approximately 30-fold and results in a monomeric cAMP-independent C subunit. The analogous residue in the mammalian C subunit is known to be phosphorylated. Peptide maps of in vivo 32P-labeled wild-type C1 and mutant C1(Ala241) suggest that Thr-241 is phosphorylated in yeast cells. Substituting Thr-241 with either aspartate or glutamate partially restored affinity for the R subunit. Uncharged and positively charged residues substituted at this site resulted in C subunits that failed to associate with the R subunit. Replacement with the phosphorylatable residue serine resulted in a C subunit with wild-type affinity for the R subunit. Analysis of this protein revealed that it appears to be phosphorylated on Ser-241 in vivo. These data suggest that the interaction between R and C involves a negatively charged phosphothreonine at position 241 of yeast C1, which can be mimicked by either aspartate, glutamate, or phosphoserine.

scholarly journals The amounts of rat liver cyclic AMP-dependent protein kinase I and II are differentially regulated by diet

1988 ◽  
Vol 256 (2) ◽  
pp. 447-452 ◽  
Author(s):  
R Ekanger ◽  
O K Vintermyr ◽  
S O Døskeland
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Restriction ◽  
Type I ◽  
Short Term ◽  
Rat Hepatocyte ◽  
Dependent Protein Kinase ◽  
Key Enzyme ◽  
Dependent Protein ◽  
Fasted Rats

1. The fluctuations in rat hepatocyte volume and protein content in response to dietary perturbations (starvation, protein restriction, refeeding) were accompanied by corresponding fluctuations in the amount of the regulatory (R) and catalytic (C) subunits of cyclic AMP-dependent protein kinase. Thus the intracellular concentration of this key enzyme was adjusted to be near constant. 2. The adjustment of cellular R was accomplished almost exclusively by regulating cytosolic RI (R subunit of type I kinase). The preferential down-regulation of cytosolic RI in response to starvation/protein restriction indicates that particulate RI and cytosolic as well as particulate RII are more resistant to breakdown during general catabolism in the hepatocyte. 3. The diet-induced fluctuations of kinase subunits were uniformly distributed in all populations of parenchymatous hepatocytes, regardless of their size and density. It is thus possible to isolate hepatocytes with uniformly altered RI/RII ratio from livers of rats with different feeding regimens. 4. The binding of endogenous cyclic AMP to RI and RII was similar in livers with high RI/RII ratio (fed rats) and low RI/RII ratio (fasted rats) as well as in hepatocytes isolated from fasted rats. Under the conditions of the experiment (short-term stimulation by glucagon), therefore, neither the dietary state nor the RI/RII ratio seemed to affect the apparent affinity of the isoreceptors for cyclic AMP. However, RI appeared to show a slightly higher co-operativity of intracellular cyclic AMP binding than did RII in all states.

scholarly journals Cloning and characterization of BCY1, a locus encoding a regulatory subunit of the cyclic AMP-dependent protein kinase in Saccharomyces cerevisiae.

1987 ◽  
Vol 7 (4) ◽  
pp. 1371-1377 ◽  
Author(s):  
T Toda ◽  
S Cameron ◽  
P Sass ◽  
M Zoller ◽  
J D Scott ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Carbon Sources ◽  
Regulatory Subunit ◽  
Dependent Protein Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Regulatory Subunits ◽  
Dependent Protein

We have cloned a gene (BCY1) from the yeast Saccharomyces cerevisiae that encodes a regulatory subunit of the cyclic AMP-dependent protein kinase. The encoded protein has a structural organization similar to that of the RI and RII regulatory subunits of the mammalian cyclic AMP-dependent protein kinase. Strains of S. cerevisiae with disrupted BCY1 genes do not display a cyclic AMP-dependent protein kinase in vitro, fail to grow on many carbon sources, and are exquisitely sensitive to heat shock and starvation.

scholarly journals Cyclic AMP-dependent protein kinase in rat mammary tissue: expression of catalytic and regulatory subunits throughout pregnancy and lactation

1994 ◽  
Vol 301 (3) ◽  
pp. 807-812 ◽  
Author(s):  
R A Gardner ◽  
M T Travers ◽  
M C Barber ◽  
W R Miller ◽  
R A Clegg
Keyword(s):  
Catalytic Activity ◽  
Protein Kinase ◽  
Mammary Development ◽  
Mammary Tissue ◽  
Early Lactation ◽  
Dependent Protein Kinase ◽  
Regulatory Subunits ◽  
C Subunit ◽  
Pregnancy And Lactation ◽  
Dependent Protein

‘Expressed’ and ‘total’ activities of cyclic AMP-dependent protein kinase (PK-A) were measured in extracts of rat mammary tissue sampled throughout pregnancy and lactation. Expression of the genes encoding the catalytic subunit (C-subunit) isoforms C alpha and C beta was examined by Northern blotting, as a function of mammary development, to determine relative levels of their respective mRNAs. The content of C-subunit protein (all isoforms) was estimated immunochemically and related to levels of C-subunit catalytic activity and of mRNAs. It was found that C-subunit isoform mRNAs are expressed co-ordinately during mammary development and that a marked decline in expression, per cell, at around parturition is paralleled by a fall in ‘total’ PK-A activity. The ‘expressed’ activity of PK-A activity underwent characteristic changes throughout pregnancy and lactation, reaching a peak late in pregnancy. The PK-A activity ratio reached a peak in early lactation. C-subunit protein mass closely parallel ‘total’ PK-A activity throughout pregnancy and lactation, thereby demonstrating the constancy of C-subunit specific catalytic activity during these developmental events. Regulatory subunits (R-subunits) were probed with the photoaffinity label 8-azido-[32P]cAMP. The abundance of R-II as a proportion of total R-subunit increased throughout pregnancy and lactation, and quantitative analysis of the photoaffinity labelling suggested inconstancy in the ratio of R:C subunits, with highest values occurring in late pregnancy/early lactation.

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