Palytoxin and the sodium/potassium pump--phosphorylation and potassium interaction.
We proposed a reaction model for investigating interactions between K+ and the palytoxin-sodium-potassium (PTX-Na+/K+) pump complex under conditions where enzyme phosphorylation may occur. The model is composed of (i) the Albers-Post model for Na+/K+-ATPase, describing Na+ and K+ pumping; (ii) the reaction model proposed for Na+/K+-ATPase interactions with its ligands (Na+, K+, ATP, ADP and P) and with PTX. A mathematical model derived for representing the reactions was used to simulate experimental studies of the PTX-induced current, in different concentrations for the pump ligands. The simulations allow interpretation of the simultaneous action of Na+/K+-ATPase phosphorylation and K+ on the PTX-induced channels. The results suggest that(i) phosphorylation increases the PTX toxic effect, increasing its affinity and reducing the K+occlusion rate, and (ii) K+ causes channel blockage, increases the toxin dissociation rate and impedes the induced channel phosphorylation, implying reduction of the PTX toxic effect.
Rodrigues
Antônio M
AM
Laboratory of Experimental and Computational Neuroscience, Biomedical Engineering Department, Federal University of São João del-Rei, Brazil.
Infantosi
Antonio F C
AF
de Almeida
Antônio-Carlos G
AC
D000178:Acrylamides / Q000737:chemistry* / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D003064:Cnidarian Venoms; D019295:Computational Biology; D007700:Kinetics; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000378:metabolism*; D000095702:Polyether Toxins
D000178:Acrylamides; D000251:Adenosine Triphosphatases; D003064:Cnidarian Venoms; D011188:Potassium; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; C010272:palytoxin; D000095702:Polyether Toxins