Calmodulin Sepharose
Calmodulin Sepharose - Related Videos
07:51
Pull-down of Calmodulin-binding Proteins
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Cited by 19 •
2012
Calmodulin (CaM) pull-down assay is an effective way to investigate the interaction of CaM with various proteins. This method uses CaM-sepharose beads for efficient and specific analysis of CaM-binding proteins. This provides an important tool to explore CaM signaling in cellular function.
01:16
Calmodulin-dependent Signaling
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2023
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change. The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
08:08
Co-Immunoprecipitation and Pull-Down Assays
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2023
Co-immunoprecipitation (CoIP) and pull-down assays are closely related methods to identify stable protein-protein interactions. These methods are related to immunoprecipitation, a method for separating a target protein bound to an antibody from unbound proteins. In CoIP, an antibody-bound protein is itself bound to another protein that does not bind with the antibody, this is followed by a separation process that preserves the protein-protein complex. The difference in pull-down assays is that...
10:36
Purification of Native Complexes for Structural Study Using a Tandem Affinity Tag Method
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Cited by 4 •
2016
The Tandem Affinity Purification (TAP) method has been used extensively to isolate native complexes from cellular extract, primarily eukaryotic, for proteomics. Here, we present a TAP method protocol optimized for purification of native complexes for structural studies.
02:21
Purification of Viral Integrase Using Heparin Affinity Chromatography
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2026
Source: Lopez Jr., M. et al. Detection and Removal of Nuclease Contamination During Purification of Recombinant Prototype Foamy Virus Integrase. J. Vis. Exp. (2017)This video demonstrates the procedure for purifying viral integrase from bacterial nuclease contamination using heparin Sepharose column chromatography followed by SDS-PAGE analysis to confirm protein purity.
FAQs
Calcium ions promote association between immobilized calmodulin and proteins carrying calmodulin-binding domains. This dependence also provides a release strategy: introducing EGTA or EDTA chelates calcium and disrupts the interaction, allowing bound proteins to elute. Thus, calcium presence governs capture, whereas calcium removal governs recovery, linking the biochemical condition directly to the separation step.
Recognition is not determined only by the presence of a potential binding sequence. The source material identifies sequence, conformation, and post-translational modification as factors that can influence how a protein is recognized by calmodulin. Calmodulin Sepharose can therefore help assess whether altered structural or modification states change binding, rather than merely asking whether a protein is present.
Washing removes components that do not associate with the immobilized calmodulin, reducing unrelated material carried forward from a complex biological sample. The remaining fraction is enriched for proteins able to interact under the selected calcium condition. This separation improves the usefulness of the recovered material for examining calmodulin-binding proteins and associated calcium-regulated signaling components.
A typical workflow establishes calcium-dependent binding, brings the biological sample into contact with the calmodulin-bearing Sepharose, and washes away unbound components. The retained proteins are then released by calcium chelation with EGTA or EDTA. This sequence separates capture from elution and produces a fraction suitable for subsequent protein characterization or interaction analysis.
Researchers can use the method when they need to enrich calmodulin-binding proteins from a complex sample or investigate protein-protein interactions involving calmodulin recognition. The recovered fraction can support characterization of calcium-regulated proteins and signaling components. Comparing which proteins bind under the assay conditions can also help examine how recognition depends on sequence, conformation, or post-translational modification.
In calcium-signaling studies, selective enrichment provides a way to examine proteins whose interactions with calmodulin respond to calcium conditions. The approach connects biochemical purification with functional questions about signaling components, including whether structural or post-translational differences influence recognition. Its use can therefore contribute both to identifying relevant binding proteins and to characterizing their calcium-regulated interactions.