Isolation and characterization of a convulxin-like protein from Crotalus durissus collilineatus venom.
A convulxin (Cvx)-like protein was isolated from Crotalus durissus collilineatus venom by a combination of molecular exclusion and reversed-phase HPLC chromatographies. The molecular mass of the Cvx-like protein in the absence and presence of DTT was 78 kDa and 12-13 kDa, respectively. The Cvx-like protein consisted of two nonidentical polypeptide chains (alpha and beta). The N-terminal amino-acid sequences of the alpha and beta subunits were GLHCPSDWYAYDGHCYKIFNEEMNWED and GFCCPSHWSSYSRYCYKFFSQEMNWEDAEK, respectively, with both subunits having a high content of Glu, Ser, Cys, and Asp. The Cvx-like protein showed high homology with other venom C-type lectins, but had low hemagglutinating activity on intact and trypsinized erythrocytes. The Cvx-like protein stimulated insulin receptor phosphorylation and potentiated insulin secretion from isolated islets in the presence of sub- (2.8 mM) or supra-physiological (16.7 mM) glucose concentrations. These results suggest that the increase in insulin secretion induced by Cvx-like protein may be mediated by a protein tyrosine kinase-dependent pathway and may involve other membrane receptors, such as GP VI or Scr family proteins.
Toyama
M H
MH
Departamento de Fisiologia e Biofísica, Instituto de Biologia, Brasil.
Carneiro
E M
EM
Marangoni
S
S
Amaral MEC
Velloso
L A
LA
Boschero
A C
AC
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D017839:Crotalus; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D037181:Lectins, C-Type; D008969:Molecular Sequence Data; D051381:Rats; D017385:Sequence Homology; D013020:South America; D013045:Species Specificity
D003435:Crotalid Venoms; D007328:Insulin; D037181:Lectins, C-Type; C028890:convulxin