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Biomedical subjects

B J Murphy

Publications and source records attributed to B J Murphy.

At least 19 recordsLinked to original sources
PubMed2001

Placenta growth factor gene expression is induced by hypoxia in fibroblasts: a central role for metal transcription factor-1.

Placenta growth factor (PlGF) is a mitogen for endothelial cells that can potentiate the growth and permeabilizing effects on endothelium of vascular endothelial growth factor. Here we report that hypoxia induces the expression of both PlGF mRNA and protein in immortalized/transformed mouse embryonic fibroblasts (mEFs) and in NIH 3T3 cells. Importantly, the magnitude of the induction of PlGF expression by hypoxia is enhanced by the presence of oncogenic Ras. To investigate the transcriptional component of hypoxia-inducible PlGF expression, we cloned and sequenced a 1350-bp fragment of the 5'-flanking region of the mouse gene. Analysis of the promoter region indicated the presence of putative consensus sequences for known hypoxia-responsive regulatory sites, including metal response elements and Sp1-like sites. In the present study, we show that the induction of PlGF expression by hypoxia is dependent on the presence of the metal response element-binding transcription factor 1 (MTF-1). Thus, in mEFs with targeted deletions of both MTF-1 alleles, hypoxia-induced increases of PIGF mRNA and protein levels were greatly attenuated compared with those in wild-type mEFs. Moreover, transient transfection of a PlGF promoter reporter gene into NIH 3T3 cells resulted in hypoxia-responsive transcriptional activation of the reporter. Finally, ectopic expression of MTF-1 resulted in increased basal transcriptional activity of a PlGF promoter reporter. Together, these findings demonstrate that the PlGF gene is responsive to hypoxia and that this response is mediated by MTF-1. It remains to be determined whether this activation is the result of direct and/or indirect transcriptional activation by MTF-1. The stimulatory effect of oncogenic Ras on the induction of PlGF expression in hypoxic cells suggests that PlGF could be an important proangiogenic factor in the tumor microenvironment.

3T3 Cells↗
PubMed2001

Evaluation of grades 3 and 4 chondromalacia of the knee using T2*-weighted 3D gradient-echo articular cartilage imaging.

OBJECTIVE: To determine the accuracy of T2*-weighted three-dimensional (3D) gradient-echo articular cartilage imaging in the identification of grades 3 and 4 chondromalacia of the knee. DESIGN AND PATIENTS: A retrospective evaluation of 80 patients who underwent both arthroscopic and MRI evaluation was performed. The 3D images were interpreted by one observer without knowledge of the surgical results. The medial and lateral femoral condyles, the medial and lateral tibial plateau, the patellar cartilage and trochlear groove were evaluated. MR cartilage images were considered positive if focal reduction of cartilage thickness was present (grade 3 chondromalacia) or if complete loss of cartilage was present (grade 4 chondromalacia). Comparison of the 3D MR results with the arthroscopic findings was performed. RESULTS: Eighty patients were included in the study group. A total of 480 articular cartilage sites were evaluated with MRI and arthroscopy. Results of MR identification of grades 3 and 4 chondromalacia, all sites combined, were: sensitivity 83%, specificity 97%, false negative rate 17%, false positive rate 3%, positive predictive value 87%, negative predictive value 95%, overall accuracy 93%. CONCLUSION: The results demonstrate that T2*-weighted 3D gradient-echo articular cartilage imaging can identify grades 3 and 4 chondromalacia of the knee.

Adolescent↗
PubMed2000

Pharmacokinetics and in vivo effects of a six-base phosphorothioate oligodeoxynucleotide with anticancer and hematopoietic activities in swine.

A short phosphorothioate oligodeoxynucleotide telomere mimic with the sequence 5'-d(TTAGGG)-3', TAG-6, has been shown to inhibit telomerase activity and have antineoplastic and hematopoietic stimulatory properties. In this study, three immature male domestic swine (weighing approximately 40 kg) were administered 200 mg/m2 of TAG-6 by continuous intravascular infusion at rates of 0.48 +/- 0.07 mg/hr for 14 days to evaluate the pharmacokinetics, toxicity, and tissue distribution. There was considerable variability (both within each animal and across animals) observed in the pharmacokinetic data. The plasma half-life (t1/2 appeared to be short enough that it could be assumed that steady state was attained by at least 96 h after the start of the infusion. The t1/2 estimates for the three pigs were 8.96, 109, and 1.97 h (the long t1/2 for pig 2 may be explained by poor parameter estimation due to the variability). The volume of distribution ranged from 9.80 to 51.8 L (0.3-1.4 L/kg), and plasma clearance estimates ranged from 0.33 to 3.46 L/h (5.5-57.7 ml/min). The average plasma concentrations at steady state were 0.845, 0.933, and 0.178 microg/ml (0.44, 0.49, and 0.093 microM) for the three animals. Nearly 30% of the administered dose was cleared through renal excretion by day 7 postinfusion. The distribution of TAG-6 was primarily to the liver and kidney, but the spleen and thyroid accumulated relatively high concentrations of TAG-6. TAG-6 was metabolized to apparently higher molecular weight products, which were observed in the urine. The size periodicity of these apparently higher molecular weight products was in 6-base intervals, which is consistent with the actions of telomerase. The infusion did not produce significant changes in serum chemistry or circulating blood cells, but a decrease in colony-forming unit-granulocyte-monocyte (CFU-GM) colony formation from BM was observed. These data suggest that TAG-6 may be a very specific pharmacophore.

Animals↗
PubMed2000

Nonsurgical breast enlargement using an external soft-tissue expansion system.

Less than 1 percent of the women interested in having larger breasts elect to have surgical augmentation mammaplasty with insertion of breast implants. The purpose of this report is to describe and test the efficacy of a nonsurgical method for breast enlargement that is based on the ability of tissues to grow when subjected to controlled distractive mechanical forces. Seventeen healthy women (aged 18 to 40 years) who were motivated to achieve breast enlargement were enrolled in a single-group study. The participants were asked to wear a brassiere-like system that applies a 20-mmHg vacuum distraction force to each breast for 10 to 12 hours/day over a 10-week period. Breast size was measured by three separate methods at regular intervals during and after treatment. Breast tissue water density and architecture were visualized before and after treatment by magnetic resonance imaging scans obtained in the same phase of the menstrual cycle. Twelve subjects completed the study; five withdrawals occurred due to protocol noncompliance. Breast size increased in all women over the 10-week treatment course and peaked at week 10 (final treatment); the average increase per woman was 98 +/- 67 percent over starting size. Partial recoil was seen in the first week after terminating treatment, with no significant further size reduction after up to 30 weeks of follow-up. The stable long-term increase in breast size was 55 percent (range, 15 to 115 percent). Magnetic resonance images showed no edema and confirmed the proportionate enlargement of both adipose and fibroglandular tissue components. A statistically significant decrease in body weight occurred during the course of the study, and scores on the self-esteem questionnaire improved significantly. All participants were very pleased with the outcome and reported that the device was comfortable to wear. No adverse events were recorded during the use of the device or after treatment. We conclude that true breast enlargement can be achieved with the daily use of an appropriately designed external expansion system. This nonsurgical and noninvasive alternative for breast enlargement is effective and well tolerated.

Adult↗
PubMed1999

Human immunodeficiency virus-1 infection requires pertussis toxin sensitive G-protein-coupled signalling and mediates cAMP downregulation.

The human immunodeficiency virus-1 (HIV-1) utilises CD4 and certain beta-chemokine receptors, mainly CCR-5 and CXCR4, for attachment and virus entry into T-lymphocytes and monocytes/macrophages. CD4 and beta-chemokine receptors participate in intracellular signalling via protein tyrosine kinases and G-protein-coupled signalling. The factors which influence HIV-1 replication and the intracellular signalling mechanisms elicited by the virus are not well understood. In this study, it was demonstrated that exposure of peripheral blood lymphocytes (PBLs) to a T-cell tropic strain of HIV-1 evokes signal(s) which results in downregulation of intracellular cAMP. In addition, pre-incubation of PBLs with the Gi-protein inhibitor Pertussis toxin mediated a significant inhibition of HIV-1 replication. These data strongly suggest that HIV-1 employs CD4 receptors and Gi-coupled proteins for entry into target cells and that productive HIV-1 infection is dependent on an active signalling event.

Benzoquinones↗
PubMed1999

Activation of metallothionein gene expression by hypoxia involves metal response elements and metal transcription factor-1.

Metallothioneins (MTs) are a family of stress-induced proteins with diverse physiological functions, including protection against metal toxicity and oxidants. They may also contribute to the regulation of cellular proliferation, apoptosis, and malignant progression. We reported previously that the human (h)MT-IIA isoform is induced in carcinoma cells (A431, SiHa, and HT29) exposed to low oxygen, conditions commonly found in solid tumors. The present study demonstrates that the genes for hMT-IIA and mouse (m)MT-I are transcriptionally activated by hypoxia through metal response elements (MREs) in their proximal promoter regions. These elements bind metal transcription factor-1 (MTF-1). Deletion and mutational analyses of the hMT-IIA promoter indicated that the hMRE-a element is essential for basal promoter activity and for induction by hypoxia, but that other elements contribute to the full transcriptional response. Functional studies of the mMT-I promoter demonstrated that at least two other MREs (mMRE-d and mMRE-c) are responsive to hypoxia. Multiple copies of either hMRE-a or mMRE-d conferred hypoxia responsiveness to a minimal MT promoter. Mouse MT-I gene transcripts in fibroblasts with targeted deletions of both MTF-1 alleles (MTF-1(-/-); dko7 cells) were not induced by zinc and showed low responsiveness to hypoxia. A transiently transfected MT promoter was unresponsive to hypoxia or zinc in dko7 cells, but inductions were restored by cotransfecting a mouse MTF-1 expression vector. Electrophoretic mobility shift assays detected a specific protein-DNA complex containing MTF-1 in nuclear extracts from hypoxic cells. Together, these results demonstrate that hypoxia activates MT gene expression through MREs and that this activation involves MTF-1.

3T3 Cells↗
PubMed1998

Impaired CD45-associated tyrosine phosphatase activity during HIV-1 infection: implications for CD3 and CD4 receptor signalling.

Proper function of the protein tyrosine phosphatase CD45 is required for the positive regulation of the activity of src tyrosine kinases p56lck and p59fyn which participate in T-cell receptor and CD4 receptor signalling. In this study, the effect of HIV-1 infection on the function of CD45-associated tyrosine phosphatase activity in the H9 T-cell line has been investigated with respect to CD3 and CD4 ligation. A significant reduction in CD45-associated phosphatase activity was observed following CD3 + CD4 ligation in virally infected cells, whereas CD45 activity was not compromised following CD3 receptor ligation. Dysfunctional CD45 activity in infected cells was not attributable to reduced receptor surface expression induced by HIV-1, since CD4, CD3 and CD45 expression levels were found to be intact. Defective CD45 activity correlated with inhibted downstream signalling events as evidenced by reduced CD4-associated tyrosine kinase activity and inhibition of PLC-gamma1. Impaired CD45 function is likely to play a critical role in the inhibition of CD3/CD4 signalling thereby contributing to HIV-1 pathogenesis.

Amino Acid Sequence↗
PubMed1998

AKAP15 anchors cAMP-dependent protein kinase to brain sodium channels.

The voltage-sensitive sodium channel is regulated by cAMP-dependent protein kinase (PKA) phosphorylation. Using purified preparations of rat brain sodium channels, we have shown that the alpha subunit was phosphorylated by a co-purifying protein kinase. The co-purifying kinase was stimulated by cAMP and phosphorylated PKA substrate peptides. Both the regulatory and catalytic subunits of PKA were detected by immunoblotting in purified sodium channel preparations. Bound PKA was immunoprecipitated with anti-SP19 antibodies directed against the sodium channel alpha subunit. PKA bound to sodium channels phosphorylated the sodium channel alpha subunit on the same four serine residues as observed with exogenously added PKA, indicating that association with the sodium channel does not restrict the sites of phosphorylation. Analysis of proteins with high affinity for the type II alpha regulatory subunit of PKA in a gel overlay assay identified a 15-kDa cAMP-dependent protein kinase-anchoring protein (AKAP) in these preparations. Determination of its amino acid sequence by mass spectrometry revealed two peptides identical to AKAP15, a recently described AKAP that targets PKA to skeletal muscle calcium channels. The co-purifying AKAP was also immunoreactive with antibodies generated against AKAP15, and antibodies directed against AKAP15 co-immunoprecipitated the sodium channel. Our results indicate that PKA is bound to brain sodium channels through interaction with AKAP15. Association of AKAP15 with both skeletal muscle calcium channels and brain sodium channels suggests that it may have broad specificity in targeting PKA to ion channels for regulation.

A Kinase Anchor Proteins↗
PubMed1998

Primary structure and function of an A kinase anchoring protein associated with calcium channels.

Rapid, voltage-dependent potentiation of skeletal muscle L-type calcium channels requires phosphorylation by cAMP-dependent protein kinase (PKA) anchored via an A kinase anchoring protein (AKAP). Here we report the isolation, primary sequence determination, and functional characterization of AKAP15, a lipid-anchored protein of 81 amino acid residues with a single amphipathic helix that binds PKA. AKAP15 colocalizes with L-type calcium channels in transverse tubules and is associated with L-type calcium channels in transfected cells. A peptide fragment of AKAP15 encompassing the RII-binding domain blocks voltage-dependent potentiation. These results indicate that AKAP15 targets PKA to the calcium channel and plays a critical role in voltage-dependent potentiation and regulation of skeletal muscle contraction. The expression of AKAP15 in the brain and heart suggests that it may mediate rapid PKA regulation of L-type calcium channels in neurons and cardiac myocytes.

A Kinase Anchor Proteins↗
PubMed1998

The redox-sensitive human antioxidant responsive element induces gene expression under low oxygen conditions.

Transient transfection studies of human HepG2 and mouse Hepa hepatocarcinoma cells with a reporter gene construct regulated by a human antioxidant responsive element (ARE) from the NQO1 gene demonstrated that the element is responsive to low oxygen conditions. The antioxidant N-acetyl L-cysteine (NAC) strongly inhibited basal aerobic reporter gene activity in HepG2 cells without obviously affecting the hypoxic induction, as is consistent with ARE sensitivity to oxidative stress in aerobic cultures. Electrophoretic mobility shift (EMS) assays of nuclear extracts of HepG2 and Hepa cells lysed under aerobic or hypoxic conditions or after exposure to the phenolic compound 3-(2)-tert-butyl-4-hydroxyanisole (BHA), showed specific and constitutive protein binding to the ARE under all of these conditions. Taken together, these findings show that the ARE can mediate gene expression in response to low oxygen conditions. Co-ordinately regulated expression of ARE-dependent genes, such as phase II detoxification enzymes, may be an important phenotype of solid tumors containing significant regions of pathophysiological hypoxia.

Acetylcysteine↗
PubMed1998

Cell cycle-based purging of lymphoma cells from bone marrow harvests using radioiodinated 5-iodo-2'-deoxyuridine.

Minimal residual disease in lymphoma patients is a major problem in the clinical management of their cancer. High-dose chemotherapy followed by autologous bone marrow transplantation has been used to treat the disease. However, residual lymphoma may be reintroduced along with the marrow if it is present in the bone marrow harvest. In this report we describe results of experiments testing the efficacy of 5-[125I]-iodo-2'-deoxyuridine (125IdU) for purging murine RAW117 large cell lymphoma cells (Joshi et al., Oncology 44, 180-185, 1987; Cancer Res. 47, 3551-3557, 1987) from bone marrow in a relevant animal model. Donor BALB/c mice were injected with murine RAW117 cells and euthanized on day 13, and their bone marrow that had been contaminated with tumor cells was harvested and treated in vitro with 125IdU or nonradioactive 127IdU (control). Nine of 10 mice receiving 127IdU-treated bone marrow contaminated with tumor cells died at an average of 17 days after injection. In comparison, 9 of 10 mice injected with 125IdU-treated bone marrow contaminated with tumor cells were still alive after 82 days. In addition, the 125IdU treatment did not diminish the formation of hematopoietic progenitor cell colonies in normal mouse and human peripheral blood stem cells.

Animals↗
PubMed1997

In vitro infection and replication of hepatitis E virus in primary cynomolgus macaque hepatocytes.

An in vitro model was developed to replicate hepatitis E virus (HEV) in normal primary cynomolgus macaque hepatocytes using a hormonally defined, serum-free medium formulation. Primary hepatocytes were infected in tissue culture following isolation by collagenase treatment of liver wedge biopsy material. Viral replication was monitored by a highly strand-specific reverse transcription-polymerase chain reaction (RT-PCR) assay, which could detect the positive- and negative-strands of HEV RNA independently in a sensitive and specific manner. Several infectious HEV (Burma strain) inocula were titered by this RT-PCR assay, and a minimum effective infectious dose was determined. Appearance of newly replicated virus was demonstrated by detection of both strands of HEV RNA in experimentally infected hepatocytes as well as the genomic positive-strand viral RNA in the culture medium. Infectivity of the virus particles present in the media was confirmed by serial passage and replication of the virus in culture. Using this in vitro infection system, a neutralization assay was developed to assess the ability of anti-HEV antibodies to block virus infection of liver cells. Results presented in this report represent the first in vitro demonstration of a neutralizing anti-HEV antibody directed against the ORF2-encoded putative capsid protein.

Animals↗
PubMed1997

Identification of a 15-kDa cAMP-dependent protein kinase-anchoring protein associated with skeletal muscle L-type calcium channels.

Voltage-dependent potentiation of skeletal muscle L-type calcium channels requires phosphorylation by cAMP-dependent protein kinase (PKA) that is localized by binding to a cAMP-dependent protein kinase-anchoring protein (AKAP). L-type calcium channels purified from rabbit skeletal muscle contain an endogenous co-purifying protein kinase activity that phosphorylates the alpha1 and beta subunits of the channel. The co-purifying kinase also phosphorylates a known PKA peptide substrate, is stimulated by cAMP, and is inhibited by PKA inhibitor peptide-(5-24), indicating that it is PKA. PKA activity co-immunoprecipitates with the calcium channel, suggesting that the channel and the kinase are physically associated. Using biotinylated type II regulatory subunit of PKA (RII) as a probe, we have identified a 15-kDa RII-binding protein in purified calcium channel preparations, which we have designated AKAP-15. Anti-peptide antibodies directed against the alpha1 subunit of the calcium channel co-immunoprecipitate AKAP-15. Together, these findings demonstrate a physical link between PKA and the calcium channel and suggest that AKAP-15 may mediate their interaction.

Amino Acid Sequence↗
PubMed1997

Comparison of molecular cytokeratin 19 reverse transcriptase polymerase chain reaction (CK19 RT-PCR) and immunocytochemical detection of micrometastatic breast cancer cells in hematopoietic harvests.

Detection of small numbers of breast cancer cells in patient blood, aphereses, and bone marrow has become increasingly important as data have accumulated showing immunocytochemically (ICC) positive tumor cells in up to 50% of women with stage I and II breast cancer, who were initially thought to be cured of their disease but later relapsed. The ability to rule out the presence of micrometastatic disease at any stage of the clinical management protocol, whether before, during, or after therapy, would provide a useful monitoring and diagnostic tool for both the clinician and the scientist. Monitoring for the presence of minimal residual disease (MRD) is traditionally performed using ICC. A more recently established RT-PCR technique uses a molecular marker (the presence of the cytokeratin 19, CK19, transcript) to identify MRD in patient samples, with a level of sensitivity reported to be one tumor cell in 10(6) nucleated cells. This level of sensitivity is generally higher than that claimed for ICC. Based on the discriminating results of this first study, a number of laboratories have evaluated this technique for its diagnostic potential. Results from several laboratories showed a higher than expected false positive rate due to a variety of identified and unidentified sources. Therefore, the current study was designed to achieve two aims: to establish the level of sensitivity and specificity of the RT-PCR technique and to dissect out the possible variables that may contribute to a false positive result using this molecular approach. To accomplish the first goal, two simulation strategies were used, limited dilution of tumor cells into apheresis harvests and semi-quantitative PCR using stepwise dilutions of extracted RNA from tumor cells in apheresis harvests. The second goal was accomplished by performing sequential blood drawings with variably timed sample processing to identify some of the more common variables (time, anticoagulant, sample sequence) that may contribute to false positive results. Of three variables investigated, including type of blood preservative, sequence of blood tube collection, and time point of sample processing, each may contribute to a false positive result. In addition to these problems, known events involving illegitimate transcription of specific genes nonspecifically in tissue is also a potential source of false positive results. These issues may be further compounded by lack of attention to the more common methodologic problems encountered in any laboratory using the PCR technique. However, recommendations can be developed for the effective application of this technique, whose greatest strength is the demonstration of tumor negativity of the sample.

Anticoagulants↗
PubMed1996

cAMP-dependent phosphorylation of two sites in the alpha subunit of the cardiac sodium channel.

The voltage-sensitive Na+ channel is responsible for generating action potentials in the heart which are critical for coordinated cardiac muscle contraction. Cardiac Na+ channels are regulated by cAMP-dependent phosphorylation, but the sites of phosphorylation are not known. Using mammalian cells expressing the rat cardiac Na+ channel (rH1) alpha subunit and site-specific antibodies, we have shown that the alpha subunit of rat heart Na+ channel is phosphorylated selectively by cAMP-dependent protein kinase (PKA) in vitro and in intact cells. Analysis of the sites of phosphorylation by two-dimensional phosphopeptide mapping and site-directed mutagenesis of fusion proteins revealed that the cardiac alpha subunit is phosphorylated selectively in vitro by PKA on Ser526 and Ser529 in the intracellular loop connecting homologous domains I and II (LI-II). These two residues were phosphorylated in intact cells expressing the rH1 alpha subunit when PKA was activated. Our results define a different pattern of phosphorylation of LI-II of cardiac and brain Na+ channels and implicate phosphorylation of Ser526 and Ser529 in the differential regulation of cardiac and brain Na+ channels by PKA.

Amino Acid Sequence↗
PubMed1996

Identification of benz(othi)azepine-binding regions within L-type calcium channel alpha1 subunits.

To identify the binding domain for diltiazem-like Ca2+ antagonists on L-type Ca2+ channel alpha1 subunits we synthesized the benzazepine [3H]benziazem as a novel photoaffinity probe. [3H]Benziazem reversibly labeled the benzothiazepine (BTZ)-binding domain of partially purified skeletal muscle Ca2+ channels with high affinity (Kd = 12 nM) and photoincorporated into its binding domain with high yield (>66%). Antibody mapping of proteolytic labeled fragments revealed specific labeling of regions associated with transmembrane segments S6 in repeats III and IV. More than 50% of the labeling was found in the tryptic fragment alanine 1023-lysine 1077 containing IIIS6 together with extracellular and intracellular amino acid residues. The remaining labeling was identified in a second site comprising segment S6 in repeat IV and adjacent residues. Unlike for dihydropyridines, no labeling was observed in the connecting IIIS5-IIIS6 linker. The [3H]benziazem photolabeled regions must be in close contact to the drug molecule when bound to the channel. We propose that the determinants for high affinity BTZ binding are located within or in close proximity to segments IIIS6 and/or IVS6. Therefore the binding domain for BTZs, like for the other main classes of Ca2+ antagonists, must be located in close proximity to pore-forming regions of the channel.

Affinity Labels↗
PubMed1996

Specific phosphorylation of a site in the full-length form of the alpha 1 subunit of the cardiac L-type calcium channel by adenosine 3',5'-cyclic monophosphate-dependent protein kinase.

Voltage-gated L-type Ca2+ channels mediate Ca2+ entry into cells in response to membrane depolarization. Ca2+ entry through the cardiac Ca2+ channel determines the rate and force of contraction, and modulation of Ca2+ channel activity by beta-adrenergic agents acting through adenosine 3',5'-cyclic monophosphate-(cAMP)-dependent protein phosphorylation contributes to physiological regulation of cardiac function by the sympathetic nervous system. Immunoblotting experiments using site-directed anti-peptide antibodies against different peptide segments indicate that the alpha 1 subunit of the cardiac L-type Ca2+ channel exists in two size forms with apparent molecular masses of 240 and 210 kDa, which we call alpha 1(242) and alpha 1(210), Alpha 1(242) corresponds to the full-length cardiac alpha 1 subunit predicted from its cDNA sequence, while alpha 1(210) is truncated at its COOH terminus. Only alpha 1(242) is phosphorylated in vitro by cAMP-dependent protein kinase. Protein microsequencing and peptide mapping of wild-type and mutant fusion proteins show that this phosphorylation occurs at serine 1928 near the COOH terminus. Phosphorylation of this residue can be detected by phosphospecific antibodies raised against the corresponding phosphopeptide. Experiments with these antibodies show that alpha 1(242) is phosphorylated in intact cells expressing the cardiac alpha 1 subunit in response to increased intracellular levels of cAMP. These results identify serine 1928 on the alpha 1 subunit as a possible site of regulation by cAMP-dependent phosphorylation.

Amino Acid Sequence↗