Binding of a native titin fragment to actin is regulated by PIP2.
Titin is a giant protein which extends from Z-line to M-line in striated muscles. We report here the purification of a 150-kDa titin fragment, obtained after V8 protease treatment of myofibrils. This polypeptide was located at the N1-line level, in a titin part known to exhibit stiff properties correlated to an association with actin. By solid or liquid phase binding assays and cosedimentation, we have clearly demonstrated a direct, saturable and relative high affinity binding of the native titin fragment to F-actin. The 150-kDa titin fragment was also shown to accelerate actin polymerization. Furthermore, the actin-titin interaction was found to be inhibited by phosphoinositides.
Astier
C
C
Laboratoire de Motilité Cellulaire EPHE, UMR 5539, Université des Sciences et Techniques du Languedoc, Montpellier, France. c-astier@crit.univ.montp2.fr
Raynaud
F
F
Lebart
M C
MC
Roustan
C
C
Benyamin
Y
Y
D000199:Actins / Q000502:physiology*; D000818:Animals; D064211:Connectin; D009124:Muscle Proteins / Q000302:isolation & purification / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D011108:Polymers; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits
D000199:Actins; D064211:Connectin; D009124:Muscle Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D011108:Polymers; D011494:Protein Kinases