Actin content determination

The MCE values are recorded for each sample, and the relative F-actin content is determined as Stimulated Sample MCF/Resting (Control) MCE. 

Although the toxin s effects on the microfilament system are easily visualized by fluorescence microscopy, it may be important to determine the changes in the ratio of cellular F- and G-actin quantitatively. Because G-actin dissolves in Triton X-100, whereas F-actin (or at least a major fraction of F-actin) does not, fractionation by detergent solubility can be used to study changes in the G- and F-actin content of cells. A different approach is the determination of G-actin content by the DNAse inhibition assay according to Blikstad (Blikstad et al., 1978). The action of DNAse in cleaving DNA is inhibited by monomeric G-actin but not by F-actin. Thus, the extent of inhibition of DNAse is proportional to the concentration of G-actin in cell lysates. 

Cell-wide photoactivation increased free barbed ends, F-actin content, and cellular locomotion, while highly localized activation generated lamellipodia and determined direction of cell locomotion. Showing all the intrinsic power of caged proteins in biological investigations in vivo, this study expanded the effective role of cofilin in contrast to motility models in vitro, where cofilin was predicted to only depolymerize F-actin. 

The profiles of the actinic flux are computed at each grid point of the model domain. To determine the absorption and scattering cross sections needed by the radiative transfer model, predicted values of temperature, ozone, and cloud liquid water content are used below the upper boundary of WRF. Above the upper boundary of WRF, fixed typical temperamre and ozone profiles are used to determine the absorption and scattering cross sections. These ozone profiles are scaled... 

In order to obtain information on the L-myosin-actin ratio without determining the total protein content, Straub (1942) converts the ATP effect into an activity. This relates the observed A%pe . to that of a normal preparation rmai) of such concentration that its viscosity... 

The minor amino acid typically present in the meat myofibrillar protein actin (also in some myosin isoforms and in dipeptide anserine, see Section 2.3.3.1.3) is L-3-methylhistidine (2-8), which is formed by methylation of histidine bound at the 73rd position of the protein chain. The functional significance of this modification of actin is not known it is probably related to the metabolism of phosphates, with which the side chain of methylhistidine interacts. Methylhistidine does not occur in other protein-rich foods such as milk, eggs and soybeans. Its contents might therefore serve as a criterion for determining the quality ingredients in meat products. 

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