Comparison of phosphorylase isoenzymes in the rabbit

Schliselfeld, Louis H.; Davis, Craig H.; Krebs, Edwin G.

doi:10.1021/bi00827a020

Cited by 40 publications

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“…Other poorly differentiated, rapid-growing hepatomas such as the Morris 3924A hepatoma give a pattern similar to that of the Novikoff hepatoma, whereas the well-differentiated, slow-growing Morris hepatoma 20 possesses both the tumor form as a minor, and the liver An antiserum was prepared as a rabbit serum globulin fraction after serial injections of a crystalline preparation of rat skeletal muscle phosphorylase prepared as described by Sevilla and Fischer (14), together with complete Freund's adjuvant. The glycogen pellets containing the enzyme were hydrolyzed with human salivary amylase, and a fixed amount, containing approximately 0.1 to 0.3 unit, was treated with antiserum essentially according to Schliselfeld et al (15). After 20 minutes' incubation at 300C, assays were conducted with 1 mM AMP; with 0.5M NaSO, (solid lines); and without Na2SO.…”

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Phosphorylase: A New Isozyme in Rat Hepatic Tumors and Fetal Liver

Sato

Morris

Weinhouse

1972

Science

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Phosphorylase: A New Isozyme in Rat Hepatic Tumors and Fetal Liver

Sato

Morris

Weinhouse

1972

Science

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“…In any case, it was demonstrated for the first time in this study that the quantity of 5'-AMP in cardiac muscle was much larger than that in skeletal one. Thus, the high active form ratio of phosphorylase in cardiac muscle seemed to be explained, if not all, by 5'-AMP, which was supported by the report of Schliselfeld, Davis and Krebs (1970). By the way, cardiac muscle 5'-AMP has been reported to be increased by ischemia (Opie 1976).…”

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confidence: 68%

Glycogen Metabolizing Enzymes Activities in Cardiac Muscle Compared with Skeletal Muscle

Tsutou¹,

Nakamura²,

Negami³

et al. 1985

Horm Metab Res

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The main energy source available to cardiac muscle is different from that available to skeletal one (Gibbs 1978). It is known that glycogen is not normally utilized by aerobic heart. However, the significance of glycogen metabolism in cardiac muscle has not been clearly elucidated. This study has been designed to assess glycogen content together with its anabolic and catabolic enzymes in cardiac and skeletal muscles with special emphasis on lower activities of glycogen metabolizing enzymes, relatively higher activity of cAMP-dependent protein kinase (protein kinase A) and possibility of ischemia-induced direct activation of phosphorylase in cardiac muscle. Materials and MethodsFed adult male rabbits were anesthetized with pentobarbital intravenously. The preparation of muscle extracts was similar to the method of Burchell, Cohen and Cohen (1976). Skeletal muscle (M. vastus lateralis) and cardiac left ventricular muscle were rapidly removed, washed by saline solution, finely minced and homogenized with 5 volume of chilled 4.0 mM EDTA-0.5 mM phenylmethylsulfonyl fluoride-0.05 mM p-tosyl-l-lysine chloromethyl ketone (pH 7.4). The homogenate was centrifuged at 12,000 g for 20 min and the supernatant was used in the present experiments. In part, for control experiment to ischemic condition, both muscles were quickly removed and frozen in liquid nitrogen. Each muscle was then ground into powder in a mortar with a pestle. The enzymes were extracted as above. Muscle phosphorylase b was prepared and glycogen synthase, phosphorylase kinase and phosphorylase were assayed as previously described (Hashimoto, Mizuta, Tsutou, Nakamura and Yamamura 1983;Mizuta, Hashimoto, Tsutou, Eishi, Takemura, Nirisawa and Namamura 1984;Tsutou, Nakamura, Negami, Mizuta, Hashimoto and Yamamura 1985). Branching enzyme,debranching enzyme, glycogen and protein concentration were assayed according to the report of Moruzzi, Bergamini and Bergamini (1981). The assay of protein kinase A was the same as the report of Kemp, Graves, Benjamini and Krebs (1977). Student's t-test was used for analyses of the data. Results and DiscussionThere are many reports on glycogen metabolism in skeletal and cardiac muscles. However, there is no comparative study of activities of glycogen metabolizing enzymes including branching and debranching enzymes. The comparison of them in both muscles was summarized in Table 1. It was shown that the activities of enzymes except for protein kinase A in cardiac muscle were lower than those in skeletal one. This suggests that cardiac muscle does not utilize glycogen efficiently as main energy source in ordinary state. Kemptide, which was used in the present study, has been known to be the most specific substrate of protein kinase A (Kemp et al. 1977). Though there were no statistical differences, the total and active form activities of protein kinase A in cardiac muscle, compared with those in skeletal one, showed a slightly higher tendency. Fig. 1 Active form ratio (%) of glycogen synthase (G.S.), phosphorylase kinase (Ph. K.) a...

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“…Interconvcrsion between these two forms by the enzymes glycogen phosphorylase kinase and protein phosphatase I [21, 221 is thought to be the principal way by which glycogenolysis is controlled in muscle [23]. Liver and brain phosphorylascs can also exist in phosphorylated/dephosphorylated states [4,6,7, 91 and exhibit differences in regulation according to their specific requirements for activity [4,6,10,[24][25][26][27].…”

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Comparative sequence analysis of rat, rabbit, and human muscle glycogen phosphorylase cDNAs

et al. 1985

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As an initial step in the investigation of the structure, evolution and developmental regulation of the glycogen phosphorylase gene family, we have isolated partial cDNAs to rat, rabbit and human muscle phosphorylase mRNAs. Sequence comparisons of these cDNAs in regions that encode portions of the enzyme located near and encompassing the C terminus show that there is a high degree of interspecies conservation of structure in this region. Conservation of amino acid and nucleotide sequence is high, approximately 96% and 90°A homology, respectively, among all three species. In addition, most of the amino acid changes that have occurred conserve the chemical nature of the amino acid side-chains affected. The changes can be easily accommodated in the rabbit muscle phosphorylase tertiary structure and appear to have little effect on the overall conformation. Interestingly the rat and human enzymes lack the carboxyl-terminal proline (residue 841) present in the rabbit enzyme and terminate a t isoleucine (residue 840). The genetic basis for this difference in carboxyl termini is unknown. However, unlike the other amino acid changes, it cannot be accounted for by a single base-pair substitution. A comparison of the 3' untranslated regions in these cDNAs shows that there has been little constraint on the evolutionary divergence of most of this region (70% homology among the three species). There are, however, two repeated segments of D N A flanking the stop codons that are identical among all three species. Similar sequences are found within regions of D N A that contain a variety of transcriptional enhancers, suggesting the possibility that the repeats may be functional Glycogen phosphorylases play a major role in regulating thc metabolic responses of mammalian tissue. The enzyme catalyzes the intracellular formation of glucose 1-phosphate from the storage polysaccharide glycogen, a function which, in muscle, is associated with the energy requirements of contraction, in liver with the maintenance of blood sugar levels, and in other tissues such as heart and brain with the possible provision of an emergency energy source during brief periods o f anoxia (for recent reviews on phosphorylase structure and function, see [I -31). In mammals, glycogen phosphorylases are widespread in their tissue distribution and comprise a family of isozymes that appear to be encoded by distinct but closely related genes. Three isozymes have been dcscribed that can be distinguished by their electrophoretic mobilities on gels and by their immunological and catalytic properties [4 -121 : a brain isozyme (also referred to as the fetal isozyme) that is predominant in adult brain and embryonic tissues; a liver enzyme and a muscle isozymes that are predominant in adult liver and skeletal muscle respectively. All three isozymes are also present to varying extents in a wide variety of other tissues [7-9, 11, 121 and

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Comparison of phosphorylase isoenzymes in the rabbit

Cited by 40 publications

References 23 publications

Phosphorylase: A New Isozyme in Rat Hepatic Tumors and Fetal Liver

Phosphorylase: A New Isozyme in Rat Hepatic Tumors and Fetal Liver

Glycogen Metabolizing Enzymes Activities in Cardiac Muscle Compared with Skeletal Muscle

Comparative sequence analysis of rat, rabbit, and human muscle glycogen phosphorylase cDNAs

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