The Toxin-Binding Protein of Sugarcane, Its Role in the Plant and in Disease Development
AUTOR(ES)
Strobel, Gary A.
RESUMO
The toxin-binding protein of sugarcane susceptible to eyespot disease also possesses raffinose-binding activity. The Km's for binding are: helminthosporoside (toxin) 6.8 × 10-5 M, raffinose 2.5 × 10-5 M, and melibiose 2.6 × 10-5 M. Evidence obtained by administering [14C]raffinose to sugarcane protoplasts suggests that this protein participates in α-galactoside transport. Cells from a resistant clone of sugarcane do not possess an active-binding protein, and likewise, do not actively take up raffinose. Interestingly, the K+, Mg++ ATPase (ATP phosphohydrolase, EC 3.6.1.3.) on the plasma membrane of the susceptible sugarcane is 30% activated by the toxin at 3 mM. In addition, toxin-treated tissue slices show a rapid uptake of 86Rb+-K+ which is in agreement with the toxin activation of the membrane K+, Mg++ ATPase. Since the ATPase does not directly interact with the toxin, the activation effect occurs by means of the toxin-binding protein. Membrane proteins may be influenced by the toxin-binding protein acting by one of several different mechanisms.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=434365Documentos Relacionados
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