The actin gelling activity of chicken gizzard α-actinin at physiological temperature is triggered by water sequestration

AbstractAt 37°C, in the presence of 6% (wv) polyethylene glycol 6000, 30 nM α-actinin from chicken gizzard induces the gelation of 12 μM actin. Static measurement shows that the addition of 30 nM α-actinin increases the rigidity of the system from 23.5 to 54 dynescm2. According to the theory of osmoelastic coupling, also large additives, such as the proteins of the cell sap, are able to cause an osmotic stress equivalent to that caused by polyethylene glycol. We thus conclude that, in vivo, α-actinin acts as an actin gelling protein

PREFERENTIAL BINDING OF ALPHA-ACTININ TO ACTIN BUNDLES

none4At 37 degrees C, the alpha-actin-F-actin binding isotherm is anomalous. In 6.7% polyethylene glycol 6000, concomitantly with the formation of actin bundles, the binding isotherm becomes hyperbolic (Kdiss. = 11.3 microM). alpha-Actinin increases the rigidity of the networks formed by actin bundles in polyethylene glycol and by paracrystalline actin in 16 mM MgCl2 but not by F-actin. It is proposed that in the cell alpha-actinin functions are mostly carried on by interaction with actin bundles.noneE GRAZI; P CUNEO; E MAGRI; C. SCHWIENBACHERGrazi, Enrico; P., Cuneo; Magri, Ermes; Schwienbacher, Christin