2′,3′‐cyclic Nucleotide 3′‐phosphohydrolase in Brains of Mutant Mice With Deficient Myelination

Kurihara, Tadashi; Nussbaum, J.L.; Mandel, P.

doi:10.1111/j.1471-4159.1970.tb02252.x

Cited by 183 publications

(52 citation statements)

References 11 publications

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“…The observation that the deficiency of PAPS-CST activity is limited to the CNS, which is in accord with the results on other enzyme activities in mutant mice [7,22] , is of great interest considering the genetic control of enzyme biosynthesis.…”

Section: Febs Leiters December 1971 3 Results and Discussionsupporting

confidence: 68%

PAPS—cerebroside sulphotransferase activity in brain and kidney of neurological mutants

1971

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Section: Febs Leiters December 1971 3 Results and Discussionsupporting

confidence: 68%

PAPS—cerebroside sulphotransferase activity in brain and kidney of neurological mutants

1971

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“…The aminopeptidase hydrolyzing Leu-Gly-Gly and the cyclic phosphatase hydrolyzing andenosine 2' : %'-cyclic phosphate were notable exceptions since their specific activity increased with purification. Present data for the phosphatase is in agreement with those of other studies [26, 41,42], that this enzyme is an intrinsic component of the myelin membrane. Although, the presence of leucine aminopeptidase based on the hydrolysis of the /3-naphthylamide derivative of leucine has been reported [9,10] it is now known that this substrate is unspecific and can represent N-terminal peptidases with wider specificity [31].…”

Section: Protein Breukdmnsupporting

confidence: 82%

Metabolic Instability of Myelin Protein and Proteolipid Fractions

Marks¹,

Mela²,

D'Monte

1971

European Journal of Biochemistry

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Turnover of protein components of myelin in vivo was shown to be comparable to that of other brain proteins. Myelin was purified, to remove soluble contamination, by water shock (fraction M,) and centrifugation on sucrose and CsCl gradients. These methods gave two fractions, one of which consisted of characteristic myelin membranes free of visible contamination (MJ, and the second consisted of fragmented membranes and vesicles (M4).Incorporation following intracisternal injection of [14C]lysine occurred a t later time periods in myelin compared to mitochondria, probably as a result of different rates for penetration of precursor. The half-lives for the different categories of protein and proteolipid components prepared by Triton X-100 acetate procedures were markedly heterogeneous. I n myelin, the highest incorporation occurred in the soluble basic proteins with half-lives of 14-21 days (fraction 111), followed by the interface (Folch-Lees, fraction 11) material with half-lives of 12 -24 days, and the insoluble proteins (Wolfgram, fractionIII) with half-lives of 28 -32 days. The half-lives varied with the pulse periods used (15-360 min) and give evidence of both short-lived and long-lived proteins. Heterogeneity of turnover was supported by the complex disc-gel patterns found with electrophoresis on acrylamide using a phenol-urea solvent system for solubilization. I n comparable mitochondria1 fractions, incorporation was highest in the interface material (half-life 6 -4 days), followed by insoluble proteins (half-life 3-6 days), and lowest in the soluble (brain) fraction (half-life 6-26 days).Considerable hydrolase activity was observed in crude fractions and in hypotonic myelin fractions, particularly acid and neutral proteinases, aminopeptidase, and monoacyl and dipeptidyl arylamidases. It appears that hydrolases associated with the sheath could be involved in turnover, but in most cases are not associated with the highly purified membranes prepared in sucrose and CsCl gradients. Purification resulted in an increased specific activity of an aminopeptidase hydrolysing Leu-Gly-Gly as the substrate, and of ribonucleoside-2' : 3'-cyclic-phosphate esterase. It is concluded that these two hydrolases are intrinsic components of the myelin sheath membranes.Alteration in the composition of myelin during growth, or in disease, is accompanied by severe malfunction of the nervous system. Despite considerable recent interest in myelin, the nature of the protein components and the manner they are complexed with lipids (proteolipids) within the sheath are poorly documented (for review see [4]). Previous studies on protein metabolism were handicapped by inadequate procedures for preparation of myelin free of contamination. The present study was aimed a t the investigation of such processes, with particular emphasis on comparison of turnover and breakdown of proteins in crude preparations and of those purified by hypotonic shock and sucrose and CsCl gradients.There have been several suggestions in the literature that breakdown...

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“…Homogenate and myelin aliquots were removed and used for protein ¡19] and 2'. 3'-cyclic nucleotide .V-phosphodiesterase (CNP; EC 3.1.4.37) determination [16], After removing ali quots for protein and enzymatic determination, myelin was delipidated with ether-ethanol (13). dried under ni trogen and stored at -80 °C.…”

Section: Biochemical Methodsmentioning

confidence: 99%

Myelin Basic Protein Deficit in the PNS of <i>mld</i> Mutant Mice Recovers during Development

1983

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Myelination was studied between 15 and 135 days postnatally in peripheral nerves of myelin deficient (mld) mice and in unaffected littermates. The nerve weights were not affected by the mutation and showed a 4-fold increase during the developmental period studied. The amounts of myelin present in peripheral nerves, as shown by biochemical and morphological techniques, were slightly reduced in mld in comparison to control mice. In controls, the concentration of myelin doubled during the investigation period. The increase of myelin basic protein (MBP) in total nerve homogenate paralleled the deposition of myelin, but the MBP concentration remained constant in normal myelin. In contrast, in mld myelin MBP concentrations were extremely low until 60 days of age and increased thereafter to reach almost normal values at 135 days. Similarly, the amounts of myelin isolated at 85 and 135 days were normal. 2',3'-Cyclic nucleotide 3'-phosphodiesterase (CNP; EC 3.1.4.37), the myelin-specific enzyme, showed normal specific activities in mld nerves. In mld and control myelin, CNP-specific activities decreased during development suggesting a preferential localization of CNP in Schwann cell plasma membranes. In contrast to the central nervous system, other myelin proteins were not altered in mld peripheral nervous system (PNS) and the very low MBP content had no severe repercussions on the composition and structure of the myelin sheath. Furthermore, Schwann cells appeared normal in mld PNS. Nevertheless, more subtle alterations could be detected. Slightly decreased amounts of myelin were observed in young mld mice and preliminary results indicate discrete alterations of the myelin periodicity. After 60 days postnatally, when the repressed MBP synthesis was removed, MBP was incorporated into the myelin sheath and the MBP deficit was nearly corrected.

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2′,3′‐cyclic Nucleotide 3′‐phosphohydrolase in Brains of Mutant Mice With Deficient Myelination

Cited by 183 publications

References 11 publications

PAPS—cerebroside sulphotransferase activity in brain and kidney of neurological mutants

PAPS—cerebroside sulphotransferase activity in brain and kidney of neurological mutants

Metabolic Instability of Myelin Protein and Proteolipid Fractions

Myelin Basic Protein Deficit in the PNS of <i>mld</i> Mutant Mice Recovers during Development

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