Protein Activity Analysis
Protein Activity Analysis - Related Videos
11:45
Quantifying Agonist Activity at G Protein-coupled Receptors
0 Views •
Cited by 10 •
2011
A method for estimating the affinity constant of an agonist for the active state (Kb) of a G protein-coupled receptor is described. The analysis provides absolute or relative measures of Kb depending on whether constitutive receptor activation is measurable. Our method applies to various responses downstream from receptor activation.
01:22
Activation and Inactivation of G Proteins
0 Views •
2023
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
08:05
Assaying Protein Kinase Activity with Radiolabeled ATP
0 Views •
Cited by 15 •
2017
Protein kinases are highly evolved signaling enzymes and scaffolds that are critical for inter- and intracellular signal transduction. We present a protocol for measuring kinase activity through the use of radiolabeled adenosine triphosphate ([γ-32P] ATP), a reliable method to aid in elucidation of cellular signaling regulation.
07:53
Visualization and Quantitative Analysis of Genotoxin-Induced PARP1/PARP2 Activation in Cells Using a Fluorescent Fusion Protein-Based Reporter
0 Views •
2026
Here, we describe a method for cell-based visualization, subcellular localization, and quantitative analysis of poly(ADP-ribose) (PAR) enriched foci in fixed mammalian cells. This assay enables the quantification of sites of DNA damage-induced PARP activation, including that associated with base excision repair or single-strand break repair, in the nuclei of genotoxin-exposed cells.
12:02
High-throughput Analysis of Mammalian Olfactory Receptors: Measurement of Receptor Activation via Luciferase Activity
0 Views •
Cited by 16 •
2014
Olfactory receptor activation patterns encode odor identity, but the lack of published data identifying odorant ligands for mammalian olfactory receptors hinders the development of a comprehensive model of odor coding. This protocol describes a method to facilitate high-throughput identification of olfactory receptor ligands and quantification of receptor activation.
FAQs
The readout should match the protein function being examined. Substrate conversion suits catalytic activity, ligand binding measures molecular recognition, phosphorylation reflects signaling-related activity, and conformational changes indicate altered protein structure. Selecting a response that directly represents the biological function makes comparisons more meaningful and helps connect experimental measurements with the protein’s role in a cellular pathway.
Protein activity can vary with pH, temperature, cofactors, mutations, inhibitors, and interacting partners. These variables may alter reaction conditions, molecular binding, protein conformation, or communication with other components. Testing them under controlled conditions allows researchers to determine whether a change reflects an intrinsic property of the protein or an influence from its biochemical environment.
Controlled conditions make it possible to attribute differences in a measured response to a specific variable. If pH, temperature, cofactors, or other components change unpredictably, substrate conversion, binding, phosphorylation, or conformation may also shift for several reasons. Consistent conditions therefore support clearer comparisons between protein forms, treatments, and experimental states.
Measurements provide a link between a protein’s molecular response and its broader biological role. For example, changes caused by a mutation, inhibitor, or interacting partner can be evaluated through a defined activity readout and then considered in relation to cellular pathways or physiological outcomes. This approach helps researchers interpret functional consequences rather than only molecular changes.
A typical workflow begins by selecting the protein function and defining a measurable response. Researchers then establish controlled conditions, introduce relevant substrates, ligands, cofactors, inhibitors, mutations, or interacting partners as appropriate, and monitor the resulting conversion, binding, phosphorylation, or conformational change. Comparing these measurements reveals how the tested condition affects protein function.
The method can compare the activity of a disease-associated protein variant with other protein forms under controlled conditions. A difference in substrate conversion, ligand binding, phosphorylation, or conformation may indicate altered function. These results help connect a molecular variant with changes in cellular pathways and provide functional context for understanding possible physiological effects.
For drug-target studies, measuring activity can show how an inhibitor affects a protein’s defined response, such as catalytic conversion or signaling-related phosphorylation. In engineered-protein research, the same strategy evaluates whether designed changes alter function under selected conditions. Both applications use measurable molecular outcomes to guide interpretation of protein performance and modification effects.