Inositol phospholipid-induced suppression of F-actin-gelating activity of smooth muscle filamin.
Filamin, a high molecular weight actin-binding protein, cross-links actin filaments and produces a gel composed of F-actin. The effects of polyphosphoinositides on the gelating activity of smooth muscle filamin were examined by measuring the low shear viscosity of the F-actin solutions containing filamin incubated with phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP), or phosphatidylinositol 4,5-bisphosphate (PIP2). Micelles of these inositol phospholipids bound to filamin inhibited the ability to form a gel of F-actin. The inhibiting activity of each phospholipid was in the following order, PIP2 greater than PIP greater than PI. The F-actin binding assay of filamin revealed that the inhibition of F-actin-gelation resulted in the loss of the F-actin-binding activity of filamin. Thus, polyphosphoinositides may play important roles in regulating the gelating activity of filamin.
Furuhashi
K
K
Laboratory of Experimental Radiology, Aichi Cancer Center Research Institute, Japan.
Inagaki
M
M
Hatano
S
S
Fukami
K
K
Takenawa
T
T
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002645:Chickens; D003285:Contractile Proteins / Q000378:metabolism*; D064448:Filamins; D005782:Gels; D005895:Gizzard, Avian / Q000378:metabolism; D007700:Kinetics; D008823:Micelles; D008840:Microfilament Proteins / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000494:pharmacology*; D011485:Protein Binding; D013329:Structure-Activity Relationship
D000199:Actins; D002352:Carrier Proteins; D003285:Contractile Proteins; D064448:Filamins; D005782:Gels; D008823:Micelles; D008840:Microfilament Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; C037178:phosphatidylinositol 4-phosphate