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Binding And Assembly Of Actin Filaments By Plasma Membranes From Dictyostelium Discoideum, M. A. Schwartz, Elizabeth J. Luna
Binding And Assembly Of Actin Filaments By Plasma Membranes From Dictyostelium Discoideum, M. A. Schwartz, Elizabeth J. Luna
Elizabeth J. Luna
The binding of native, 125I-Bolton-Hunter-labeled actin to purified Dictyostelium discoideum plasma membranes was measured using a sedimentation assay. Binding was saturable only in the presence of the actin capping protein, gelsolin. In the presence of gelsolin, the amount of actin bound at saturation to three different membrane preparations was 80, 120, and 200 micrograms/mg of membrane protein. The respective concentrations of actin at half-saturation were 8, 12, and 18 micrograms/ml. The binding curves were sigmoidal, indicating positive cooperativity at low actin concentrations. This cooperativity appeared to be due to actin-actin associations during polymerization, since phalloidin converted the curve to a …
Smooth Muscle Archvillin: A Novel Regulator Of Signaling And Contractility In Vascular Smooth Muscle, Samudra S. Gangopadhyay, Norio Takizawa, Cynthia Gallant, Amy L. Barber, Hyun-Dong Je, Tara C. Smith, Elizabeth J. Luna, Kathleen G. Morgan
Smooth Muscle Archvillin: A Novel Regulator Of Signaling And Contractility In Vascular Smooth Muscle, Samudra S. Gangopadhyay, Norio Takizawa, Cynthia Gallant, Amy L. Barber, Hyun-Dong Je, Tara C. Smith, Elizabeth J. Luna, Kathleen G. Morgan
Elizabeth J. Luna
The mechanisms by which protein kinase C (PKC) and extracellular-signal-regulated kinases (ERK1/2) govern smooth-muscle contractility remain unclear. Calponin (CaP), an actin-binding protein and PKC substrate, mediates signaling through ERK1/2. We report here that CaP sequences containing the CaP homology (CH) domain bind to the C-terminal 251 amino acids of smooth-muscle archvillin (SmAV), a new splice variant of supervillin, which is a known actin- and myosin-II-binding protein. The CaP-SmAV interaction is demonstrated by reciprocal yeast two-hybrid and blot-overlay assays and by colocalization in COS-7 cells. In differentiated smooth muscle, endogenous SmAV and CaP co-fractionate and co-translocate to the cell cortex after …