Tyrosine Phosphorylantion State-Sensitive Antibodies Protein tyrosine kinases (PTKs) are a diverse lot, including both transmembrane and soluble cytoplasmic enzymes. Roughly 10 percent of a cell's proteins are subject to covalent modification via phosphorylation, but tyrosine (Tyr) residues are modified in only about one out of every 100 protein phosphorylation events. When Tyr-phosphorylation occurs, cells pay heed. PTKs play vital roles in a wide variety of cellular processes, including gro

Chemiluminescent Gene Reporter Systems Features of Luminometers How is the expression of a given gene controlled? That is a question asked of many in the biological and medical sciences. "Reporter genes," which encode quantifiable enzymes or proteins, are often employed by researchers seeking to better understand how the expression of genes of interest is controlled. In these assays, the coding region of the gene under study is replaced with the sequence that encodes the reporter gene. Report

Fluorescence microscopy of calcein-labeled cells. The Influx™ cell-loading reagent was used to load RBL cells with calcein. The image was acquired using a fluorescence microscope equipped with a cooled CCD camera and a bandpass filter set appropriately for fluorescein. The micrograph was reprinted with permission from Molecular Probes, Inc. Do you need to "light up" your cells with a colorful tracer or study the effects of loading cells with a given macromolecule? Representatives at Mol

Table of Licensed Providers of Molecular Beacons and Kits Using molecular beacons for spectral genotyping. Differently-colored molecular probes specific for the wild-type and mutant alleles are designed. DNA amplified from homozygous wild-type individuals binds only to the fluorescein-labeled molecular beacons (left). DNA from homozygous mutants binds only the tetramethylrhodamine-labeled molecular beacons (right). Both types of molecular probes will bind to amplicons generated from the DNA

HeLa lysates were oxidized by the addition of H2O2 (hydrogen peroxide) for 0, 0.5 or 3.5 hours. Afterwards, cell lysates from the control or H2O2-treated samples were treated +/- dinitriphenylhydrazine, then separated by PAGE and transferred to a nitrocellulose membrane. Dinitrophenylated proteins were immunodetected using the anti-DNP antibody provided in the kit. The lanes contain: (1) dinitrophenylated molecular weight standards; (2) DNP-modified HeLa control cells; (3) DNP-modified, 0.5-hou

Schematic illustration of the LexA-based yeast two-hybrid interaction. Source: OriGene Technologies, Inc. 97/98 Catalog. Reprinted with permission. The DupLEX-ATM system from OriGene Technologies is a LexA-based two-hybrid assay for the detection of protein-protein interactions in vivo (J. Gyuris et al., Cell 75:791-803, 1993). The LexA system is conceptually similar to the prototypical GAL4-based two-hybrid system, both of which are based on the bipartate nature of yeast transcriptional acti

Figure 2. Promega's DLRTM Assay System. As the sun goes down you see the recurring yet sporadic glow of fireflies around you. The flash of the common firefly (Photinus pyralis) is behavioral display at its finest. Flying males flash at intervals of about seven seconds, while nonflying females flash back with a latency of two seconds. Luciferase from the common firefly has been employed as a biological reporter for several years, and recently, Promega (Madison, Wis.) has combined firefly lucife

Date: July 20, 1998RT-PCR Kits Reverse transcription followed by the polymerase chain reaction (RT-PCR) has become one of the great "workhorse" techniques of today's labs. It is often used as a method for generating needed reagents, including complementary DNA (cDNA) inserts for cloning, cDNA libraries, and templates for in vitro transcription. None of the other commonly used methods for measuring the steady-state levels of individual RNAs (such as Northern or dot blotting, RNase or S1 nuclease

Date: May 11, 1998 Author: Deborah A. Wilkinson Products for the Chemiluminescent Detection of DNA t's late at night. You've added radiolabeled probe to your Southern blot and just placed it in the incubator. Time to go home! But not quite. Now you have to clean up the radioactive waste that oozed out while you were sealing the bag. "There has to be a better way," you think. Well, you might want to consider one of the nonradioactive, chemiluminescent detection systems. The high backgrounds and

Sensitivity, ease of use, and shelf life are all considerations in choosing detection systems for Western blots and dot blots. Chemiluminescent substrates allow the sensitive detection of targeted proteins in immunoblotting protocols with stable, hard-copy results on film-all without the hazards and other problems associated with the use of radioactive probes. Numerous chemiluminescent substrates are commercially available. They generally consist of luminol and H2O2 with undisclosed chemical e