Purification of Cortactin Using Anion Exchange Chromatography

Cortactin is an actin-binding protein that has been shown to be involved in cellular migration and metastases in cancer. Bacterially expressed and purified cortactin protein is often used in in vitro assays to examine cortactin’s role in promoting cell migration via actin remodeling. Cortactin has a theoretical molecular weight of 60 kDa; however, using SDS-PAGE analysis, the protein runs as two bands of molecular weights 80 kDa and 85 kDa, suggesting that cortactin has an unusual protein folding pattern. Our current lack of understanding of cortactin structure limits our ability to determine the role of cortactin in facilitating motility phenotypes. To elucidate the forms of cortactin produced from bacterially expressed and purified cortactin protein, we used a two-step purification system including affinity purification and anion exchange chromatography. After analysis with non-denaturing polyacrylamide gel electrophoresis, we found cortactin protein from different anion chromatography elution fractions did not separate to similar locations on the gel across all fractions. We hypothesize that the variations in the bands are a result of different folding patterns of cortactin protein in what was once thought of as a homogenous protein pool. When testing the role of cortactin in mediating cell migration, these folding differences may have significant effects on the results of functional assays such as actin polymerization or sedimentation

Sentenced for a “Crime” the Government Did Not Prove: Jones v. United States and the Constitutional Limitations on Factfinding by Sentencing Factors Rather Than Elements of the Offense

Priester argues that the Constitution does restrict the power of the legislature by requiring that certain facts be proved as elements of the offense. He notes the Supreme Court\u27s missed opportunity in Jones v. United States to adopt the test proposed by Justice Scalia

Sentenced for a “Crime” the Government Did Not Prove: Jones v. United States and the Constitutional Limitations on Factfinding by Sentencing Factors Rather Than Elements of the Offense

Priester argues that the Constitution does restrict the power of the legislature by requiring that certain facts be proved as elements of the offense. He notes the Supreme Court\u27s missed opportunity in Jones v. United States to adopt the test proposed by Justice Scalia

How dominant is the vacuum?

It would be hard to find a cosmologist today who does not believe that the vast bulk of the Universe (ninety-five percent or more) is hidden from our eyes. We review the evidence for this remarkable consensus, and for the latest proposal, that the mysterious dark matter consists of as many as {\em four separate ingredients}: baryons, massive neutrinos, ``exotic'' dark matter particles, and vacuum energy, also known as the cosmological constant (Lambda). Of these, only baryons fit within standard theoretical physics; the others, if their existence is confirmed, will mean rewriting textbooks. New experimental evidence has recently appeared for and against all four components, so that the subject is in a state of turmoil and excitement. The past three years in particular have seen the fourth (vacuum) component come into new prominence, largely at the expense of the third (exotic dark matter). We conclude our review by exploring the possibility that the energy density of the vacuum is in fact so dominant as to leave little room for significant amounts of exotic dark matter.Comment: 25 pp, 11 figs. References updated, expanded to match version in press: Naturwissenschaften V. 88, Nr. 6 (2 July 2001

Relation between theoretical and observational models of the upper atmosphere

Relation between theoretical and observational models of atmospheric properties and changes during decreasing solar activit

Atmospheric densities from Explorer 17 density gauges and a comparison with satellite drag data

Atmospheric density data from Explorer XVII GAUGES and satellite drag dat

On the Origin of Very Wide Lyα\alpha-Absorption-Lines in Quasar Spectra

We present a new explanation for the very wide absorption features in quasar spectra. In our model, a very wide absorption feature will originate, when the line of sight crosses a bubble wall tangentially. We demonstrate this on the quasar pair (2138-4427), (2139-4434). Both show two very wide absorption lines in their spectra at the same redshift. The bubble wall model can explain these observations in low density Friedmann-Lemaitre models with spherical metric. It contradicts models with euclidian or hyperbolic metric.Comment: Latex, 6 pages, Figures available at [email protected]

An investigation of the observability of ocean-surface parameters using GEOS-3 backscatter data

The degree to which ocean surface roughness can be synoptically observed through use of the information extracted from the GEOS-3 backscattered waveform data was evaluated. Algorithms are given for use in estimating the radar sensed waveheight distribution or ocean-surface impulse response. Other factors discussed include comparisons between theoretical and experimental radar cross section values, sea state bias effects, spatial variability of significant waveheight data, and sensor-related considerations