Phosphatidylinositol 3-kinase binds to profilin through the p85 alpha subunit and regulates cytoskeletal assembly.
Phosphatidylinositol 3-kinase (PI3-K), endowed with catalytic (110kDa) and regulatory (85kDa) subunits co-precipitates with anti-tyrosine antibodies in mitogen-activated cells. Association of PI3-K with cytoskeleton activates its catalytic activity through undeciphered mechanisms. Recently Singh et al., (Biochemistry, 35, 16544-16549, 1996) have shown that profilin activates PI3-K activity in a concentration-dependent manner. Consequently, we investigated the interaction between the PI3-K and profilin employing the GSTp85 alpha fusion protein and the results indicate a specific interaction between profilin and p85 alpha. The effect of p85 alpha/profilin complex on polymerization of actin monomers was monitored fluorimetrically employing pyrene-labelled actin monomers. It was noted that p85 alpha/profilin complex inhibits actin polymerization suggesting that profilin can simultaneously bind to actin as well as to p85 alpha. The affinity of p85 alpha/profilin complex to actin increases in the presence of p85 alpha subunit of PI3-K as compared to profilin itself.
Bhargavi
V
V
Department of Biochemistry, Osmania University, Hyderabad, India.
Chari
V B
VB
Singh
S S
SS
D000199:Actins / Q000378:metabolism*; D001704:Biopolymers / Q000378:metabolism; D003285:Contractile Proteins; D003599:Cytoskeleton / Q000378:metabolism*; D015151:Immunoblotting; D008840:Microfilament Proteins / Q000378:metabolism* / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry / Q000378:metabolism*; D051304:Profilins; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D000199:Actins; D001704:Biopolymers; D003285:Contractile Proteins; D008840:Microfilament Proteins; D051304:Profilins; D011993:Recombinant Fusion Proteins; D019869:Phosphatidylinositol 3-Kinases