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001-es BibID:	BIBFORM028262
Első szerző:	Dombrádi Viktor (biokémikus)
Cím:	The association of phosphorylase kinase with rabbit muscle T-tubules / V. Dombrádi, S. R. Silberman, E. Y. C. Lee, A. H. Caswell, N. R. Brandt
Dátum:	1984
ISSN:	0003-9861
Megjegyzések:	Evidence is presented for the association of a phosphorylase kinase activity with transverse tubules as well as terminal cisternae in triads isolated from rabbit skeletal muscle. This activity remained associated with T-tubules throughout the purification of triad junctions by one cycle of dissociation and reassociation. The possibility that the presence of phosphorylase kinase in these highly purified membrane vesicle preparations was due to its association with glycogen was eliminated by digestion of the latter with alpha-amylase. The phosphorylase kinase activity associated with the T-tubule membranes was similar to that reported for other membrane-bound phosphorylase kinases. The enzyme had a high pH 6.8/pH 8.2 activity ratio (0.4-0.7) and a high level of Ca2+ independent activity (EGTA/Ca2+ = 0.3-0.5). The kinase activated and phosphorylated exogenous phosphorylase b with identical time courses. When mechanically disrupted triads were centrifuged on continuous sucrose gradients, the distribution of phosphorylase kinase activity was correlated with the distribution of a Mr 128,000 polypeptide in the gradients. This polypeptide and a Mr 143,000 polypeptide were labeled with 32P by endogenous and exogenous protein kinases. These findings suggest that the membrane-associated phosphorylase kinase may be similar to the cytosolic enzyme. Markers employed for the isolated organelles included a Mr 102,000 membrane polypeptide which followed the distribution of Ca2+-stimulated 3-O-methylfluorescein phosphatase activity, which is specific for the sarcoplasmic reticulum. A Mr 72,000 polypeptide was confirmed to be a T-tubule-specific protein. Several proteins of the triad component organelle were phosphorylated by the endogenous kinase in a Ca2+/calmodulin-stimulated manner, including a Mr ca. 72,000 polypeptide found only in the transverse tubule.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban phosphorylase kinase T-tubule külföldön készült közlemény
Megjelenés:	Archives Of Biochemistry And Biophysics. - 230 : 2 (1984), p. 615-630. -
További szerzők:	Silberman, Steven R. Lee, Ernest Y. C. Caswell, A. H. Brandt, N. R.
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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001-es BibID:	BIBFORM028263
Első szerző:	Silberman, Steven R.
Cím:	Isolation and characterization of rabbit skeletal muscle protein phosphatases C-I and C-II / Steven R. Silberman, Maria Speth, Ramakrishna Nemani, Mahrukh K. Ganapathi, Viktor Dombrádi, Herve Paris, Ernest Y. C. Lee
Dátum:	1984
ISSN:	1083-351X
Megjegyzések:	Previous studies have shown that phosphorylase phosphatase can be isolated from rabbit liver and bovine heart as a form of Mr approximately 35,000 after an ethanol treatment of tissue extracts. This enzyme form was designated as protein phosphatase C. In the present study, reproducible methods for the isolation of two forms of protein phosphatase C from rabbit skeletal muscle to apparent homogeneity are described. Protein phosphatase C-I was obtained in yields of up to 20%, with specific activities toward phosphorylase a of 8,000-16,000 units/mg of protein. This enzyme represents the major phosphorylase phosphatase activity present in the ethanol-treated muscle extracts. The second enzyme, protein phosphatase C-II, had a much lower specific activity toward phosphorylase a (250-900 units/mg). Phosphatase C-I and phosphatase C-II had Mr = 32,000 and 33,500, respectively, as determined by sodium dodecyl sulfate disc gel electrophoresis. The two enzymes displayed distinct enzymatic properties. Phosphatase C-II was associated with a more active alkaline phosphatase activity toward p-nitrophenyl phosphate than was phosphatase C-I. Phosphatase C-II activities were activated by Mn2+, whereas phosphatase C-I was inhibited. Phosphatase C-I was inhibited by rabbit skeletal muscle inhibitor 2 while phosphatase C-II was not inhibited. Both enzymes dephosphorylated glycogen synthase and phosphorylase kinase, but displayed different specificities toward the alpha- and beta-subunit phosphates of phosphorylase kinase (Ganapathi, M. K., Silberman, S. R., Paris, H., and Lee, E. Y. C. (1980) J. Biol. Chem. 246, 3213-3217). The amino acid compositions of the two proteins were similar. Peptide mapping of the two proteins showed that they are distinct proteins and do not have a precursor-proteolytic product relationship.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban protein phosphatase C-I protein phosphatase C-II külföldön készült közlemény
Megjelenés:	The Journal of Biological Chemistry. - 259 : 5 (1984), p. 2913-2922. -
További szerzők:	Speth, Maria Nemani, Ramakrishna Ganapathi, Mahrukh K. Paris, Herve Lee, Ernest Y. C. Dombrádi Viktor (1953-) (biokémikus)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat
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