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saxitoxin receptor of nerve cells
1180
Third International Symposium
Data obtained from immunocytochemistry (polyclonal antibodies to AChE) indicated that the total number of AChE molecules was roughly the same in injected and wntralateral sides. Autoradiographic studies with FAS-I125 showed a strong reaction in AChE-positive areas, and confirmed the immunocytochemical results. The recovery of the AChE activity, being very slow, starts at the cell bodies of big striatal neurons and spreads through the fibers . Globally, these results show that FAS inhibition triggers a functional blockade of AChE activity, meanwhile the actual quantity of AChE protein is preserved. Then, a restoration of enzymatic activity may require a de novo protein synthesis. This work was partially supported by the International Program in the Chemical Sciences (IPICS). Development of the sodium channel tetrodotoxitr/saxitoxin receptor of nerve cells . R. Vtitm~s, D. B~t.et, M. E.
PGo, C. CASrILIA, G. Vtt.t~a~s, G. S~v~xw and F. SAxc~z (Instituto International de Estudios Avan7ados (IDEA), Apartado 17606, Caracas 10I5A, Venezuela). Tstxoootoxuv (TTX) and saxitoxin (STX) specifically bind to the Na channel of nerve and other excitable cells. These toxins have been key tools in the purification and reconstitution of Na channels of invertebrates and vertebrates . Preservation of the TTX/STX receptor is considered an indication of the presence of functional Na channels . The common component of all known Na channels purified from different animal species is a 260 Kp glycoprotein . Previous studies revealed that Na channels can be functionally reconstituted when the wrresponding 260 Kp glywprotein is incorporated in an appropriate lipid bilayer. The mRNA corresponding to the 260 KD component, even in rat brain where Na channels are wnsidered heterotrimeric complexes, is also sufficient to induce the expression of functional Na channels when injected in Xenopus oocytes. The primary structure of three closely related rat brain Na channels has been determined . We have utilized a cDNA probe, which recognizes all rat brain Na channel transcripts, and 'H-STX to study the time worse of Na channel transcription and expression during rat forebrain development. We have found that Na channel mRNA increases after birth to reach a maximum at day 8. The saxitoxin receptors in the plasma membranes also increase following the same time worse. Thus, the amount of Na channels, as determined by specific'H-STX binding, appears to depend on the abundance of Na channel mRNA .
Effect of excitatory amino acids and Ca=* on phosphorylation of CNS proteins in adult and young rats . T . WoncxuK and R. Ronxtcxr (Departamento de Bioquimica, Instituto de Biociencias, UFRGS, Porto Alegre,
RS, Brazil) .
IT is known that the activation of specific excitatory amino acid recognition sites stimulates the hydrolysis of membrane inositol phospholipida in rat hippocampal slices from young rats (NtCOiEI17 et al., 1986). This
stimulation declines during postnatal development . We are investigating the effect of glutamate and glutamate agoniats on the phosphorylation of various substrates in slioev of rat hippocampus . Slices were prepared with a McIlwain tissue chopper from young rats (betwcen 10-16 days) and the inwrporation of'=P into proteins was analysed by high resolution two-dimensional electrophoresis, sutoradiography of the gels and quantification by densitometry . In young rats glutamate gave a small increase in the inwrporation of uP into specific substrates of protein kinase C and a much greater increase into a characteristic protein of the hippocampus (ppH47). This effect was not observed in adult rats. In adult rats the absence of Ca'* resulted in the loss of ppH47 phoaphorylation . This effect was not observed in slices from 10-16 days old animals, where the absence of Ca=* stimulated the phosphorylation of ppH47. These results suggest the participation of excitatory amino acids in the regulation of ppH47 phoaphorylation . Moreover, the Ca'* requirement of the basal phosphorylation of this system increases with age in hippocampal slices . Work supported by (FAPERGS ; FINEP; CNPQ). Nteot$rrt et al. (1986) !. Newochem . 46, 40-46.
Thrombus-lite enzyme and proteinases I mid IIjrom Lachesis muta snake venous mechmtism ojaction on feMinogrn.
A. Yf x~Qité,' E. RoowQvEZ,' E. Eswaex~ and N. M~=('Laboratory of Molecular Biology, ICBAR San Marwa University Lima-Peru; =Department of Physiology and Biochemistry, King's College, London, U.K.). A snror on hydrolysis of human and bovine fibrinogen has been carried out using purified proteinases from the venom of Peruvian snake Ladtcris mute. Thrombin-like enzyme was isolated by Y~ ttt.st?vé et al. (1989) method through two steps on Stphadex G-100 by DEAE~ellulose column while proteinsee I and II were purified using Sephadex G-100 and two wlumns of DEAE-cellulose aoocording to Roowauez and Yxxt~ué (1990).
Third International Symposium
Data obtained from immunocytochemistry (polyclonal antibodies to AChE) indicated that the total number of AChE molecules was roughly the same in injected and wntralateral sides. Autoradiographic studies with FAS-I125 showed a strong reaction in AChE-positive areas, and confirmed the immunocytochemical results. The recovery of the AChE activity, being very slow, starts at the cell bodies of big striatal neurons and spreads through the fibers . Globally, these results show that FAS inhibition triggers a functional blockade of AChE activity, meanwhile the actual quantity of AChE protein is preserved. Then, a restoration of enzymatic activity may require a de novo protein synthesis. This work was partially supported by the International Program in the Chemical Sciences (IPICS). Development of the sodium channel tetrodotoxitr/saxitoxin receptor of nerve cells . R. Vtitm~s, D. B~t.et, M. E.
PGo, C. CASrILIA, G. Vtt.t~a~s, G. S~v~xw and F. SAxc~z (Instituto International de Estudios Avan7ados (IDEA), Apartado 17606, Caracas 10I5A, Venezuela). Tstxoootoxuv (TTX) and saxitoxin (STX) specifically bind to the Na channel of nerve and other excitable cells. These toxins have been key tools in the purification and reconstitution of Na channels of invertebrates and vertebrates . Preservation of the TTX/STX receptor is considered an indication of the presence of functional Na channels . The common component of all known Na channels purified from different animal species is a 260 Kp glycoprotein . Previous studies revealed that Na channels can be functionally reconstituted when the wrresponding 260 Kp glywprotein is incorporated in an appropriate lipid bilayer. The mRNA corresponding to the 260 KD component, even in rat brain where Na channels are wnsidered heterotrimeric complexes, is also sufficient to induce the expression of functional Na channels when injected in Xenopus oocytes. The primary structure of three closely related rat brain Na channels has been determined . We have utilized a cDNA probe, which recognizes all rat brain Na channel transcripts, and 'H-STX to study the time worse of Na channel transcription and expression during rat forebrain development. We have found that Na channel mRNA increases after birth to reach a maximum at day 8. The saxitoxin receptors in the plasma membranes also increase following the same time worse. Thus, the amount of Na channels, as determined by specific'H-STX binding, appears to depend on the abundance of Na channel mRNA .
Effect of excitatory amino acids and Ca=* on phosphorylation of CNS proteins in adult and young rats . T . WoncxuK and R. Ronxtcxr (Departamento de Bioquimica, Instituto de Biociencias, UFRGS, Porto Alegre,
RS, Brazil) .
IT is known that the activation of specific excitatory amino acid recognition sites stimulates the hydrolysis of membrane inositol phospholipida in rat hippocampal slices from young rats (NtCOiEI17 et al., 1986). This
stimulation declines during postnatal development . We are investigating the effect of glutamate and glutamate agoniats on the phosphorylation of various substrates in slioev of rat hippocampus . Slices were prepared with a McIlwain tissue chopper from young rats (betwcen 10-16 days) and the inwrporation of'=P into proteins was analysed by high resolution two-dimensional electrophoresis, sutoradiography of the gels and quantification by densitometry . In young rats glutamate gave a small increase in the inwrporation of uP into specific substrates of protein kinase C and a much greater increase into a characteristic protein of the hippocampus (ppH47). This effect was not observed in adult rats. In adult rats the absence of Ca'* resulted in the loss of ppH47 phoaphorylation . This effect was not observed in slices from 10-16 days old animals, where the absence of Ca=* stimulated the phosphorylation of ppH47. These results suggest the participation of excitatory amino acids in the regulation of ppH47 phoaphorylation . Moreover, the Ca'* requirement of the basal phosphorylation of this system increases with age in hippocampal slices . Work supported by (FAPERGS ; FINEP; CNPQ). Nteot$rrt et al. (1986) !. Newochem . 46, 40-46.
Thrombus-lite enzyme and proteinases I mid IIjrom Lachesis muta snake venous mechmtism ojaction on feMinogrn.
A. Yf x~Qité,' E. RoowQvEZ,' E. Eswaex~ and N. M~=('Laboratory of Molecular Biology, ICBAR San Marwa University Lima-Peru; =Department of Physiology and Biochemistry, King's College, London, U.K.). A snror on hydrolysis of human and bovine fibrinogen has been carried out using purified proteinases from the venom of Peruvian snake Ladtcris mute. Thrombin-like enzyme was isolated by Y~ ttt.st?vé et al. (1989) method through two steps on Stphadex G-100 by DEAE~ellulose column while proteinsee I and II were purified using Sephadex G-100 and two wlumns of DEAE-cellulose aoocording to Roowauez and Yxxt~ué (1990).