Tubulin and MAP2 regulate the PCSL phosphatase activity. A possible new role for microtubular proteins.
Tubulin can stimulate specifically the aryl phosphatase activity of the low-Mr polycation-stimulated (PCSL) phosphatase, measured as p-nitrophenyl phosphatase activity, or using reduced carboxamidomethylated and maleylated (RCM) lysozyme, phosphorylated on tyrosyl residues, as a substrate. This stimulation is independent of the degree of polymerization of tubulin (A50 = 60 nM) and is due to an increase in Vmax. It is mechanistically different from the ATP-induced activation and resistant to heat and trypsin treatment. Chymotrypsin destroys the stimulatory effect of tubulin. The polycation-stimulated phosphorylase phosphatase activity is inhibited by tubulin, probably by a polycation/polyanion interaction. The microtubule-associated protein, MAP2, is inhibitory to the p-nitrophenyl phosphatase activity and tubulin can eliminate this inhibitory effect. MAP2 also inhibits the polycation-stimulated phosphorylase phosphatase activity.
Jessus
C
C
Laboratoire de Physiologie de la Reproduction, Université Pierre et Marie Curie, Paris.
Goris
J
J
Cayla
X
X
Hermann
J
J
Hendrix
P
P
Ozon
R
R
Merlevede
W
W
D009597:4-Nitrophenylphosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008869:Microtubule-Associated Proteins / Q000494:pharmacology*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010765:Phosphorylase Phosphatase / Q000037:antagonists & inhibitors; D014404:Tubulin / Q000494:pharmacology*; D014981:Xenopus
D008869:Microtubule-Associated Proteins; D014404:Tubulin; D000255:Adenosine Triphosphate; D010765:Phosphorylase Phosphatase; D010744:Phosphoric Monoester Hydrolases; D009597:4-Nitrophenylphosphatase; D008274:Magnesium