Sequestered actin in chick embryo fibroblasts.
Chick embryo fibroblasts contain about 75-100 microM unpolymerized actin and at least four proteins which can bind actin monomers, actin depolymerizing factor (ADF), gelsolin, profilin, and thymosin beta4 (Tbeta4). Fibroblast extracts are analyzed by non-denaturing polyacrylamide gel electrophoresis and immunoblotting where most of the G-actin is detected as a complex with Tbeta4. When fibroblast extracts are fractionated by gel filtration and the fractions are analyzed by PAGE and HPLC, most of the G-actin elutes in a peak that also contains Tbeta4 at an overall molar ratio of 1.9:1 relative to actin. Gelsolin, profilin, and ADF are also detectable in the gel filtration eluate and at least partly coelute with actin, and account for only a minor fraction of the soluble actin pool. These observations indicate that under the growth conditions studied, Tbeta4 is the major actin-sequestering protein in fibroblasts.
Nagamalleswari
K
K
Department of Cell and Developmental Biology, University of Pennsylvania, PA, USA.
Safer
D
D
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D003285:Contractile Proteins; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D018260:Gelsolin / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D051304:Profilins; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D013947:Thymosin / Q000378:metabolism; D000099201:Thymosin beta(4)
D000199:Actins; D003285:Contractile Proteins; D018260:Gelsolin; D008840:Microfilament Proteins; D051304:Profilins; D013947:Thymosin; D000099201:Thymosin beta(4)