Related Experiment Video

Updated: Jun 5, 2026

Proteomics to Identify Proteins Interacting with P2X2 Ligand-Gated Cation Channels
16:36

Proteomics to Identify Proteins Interacting with P2X2 Ligand-Gated Cation Channels

Published on: May 18, 2009

The Ca2+ channel beta4c subunit interacts with heterochromatin protein 1 via a PXVXL binding motif

Xingfu Xu1, Yoon J Lee, Johanna B Holm

  • 1Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.

The Journal of Biological Chemistry
|January 12, 2011
PubMed

Insights

A novel truncated beta 4c subunit of voltage-gated calcium channels interacts with heterochromatin protein 1γ. This interaction suggests new roles in epigenetic regulation and gene expression within the cell nucleus.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Genetics

Background:

  • Beta subunits of voltage-gated calcium channels primarily regulate alpha-1 subunits.
  • Emerging evidence highlights Ca(2+) channel-independent functions of beta subunits, including gene expression and developmental roles.
  • The beta 4c subunit, an alternatively spliced variant, is identified in the human brain.

Purpose of the Study:

  • To identify and characterize novel interactions of the beta 4c subunit.
  • To investigate the functional implications of beta 4c subunit interactions in the nucleus.
  • To explore the role of beta 4c in epigenetic regulation.

Main Methods:

  • Identification of alternatively spliced beta 4c subunit in human brain.
  • Expression analysis in vestibular neuron nuclei.
  • Biochemical assays including pull-down assays, nuclear magnetic resonance (NMR), and isothermal titration calorimetry (ITC).
  • Site-directed mutagenesis to identify interaction motifs.
  • NMR-based molecular docking.

Main Results:

  • The beta 4c subunit is highly expressed in the nuclei of human vestibular neurons.
  • Beta 4c directly interacts with the chromo shadow domain (CSD) of heterochromatin protein 1γ (HP1γ).
  • Interaction is mediated by a PXVXL consensus motif on the beta 4c C-terminus, linking it to epigenetic proteins.
  • An NMR-based docking model reveals beta 4c complexed with dimerized CSD.

Conclusions:

  • The beta 4c subunit possesses Ca(2+) channel-independent nuclear functions.
  • Its interaction with HP1γ places it within the family of PXVXL proteins involved in epigenetic regulation.
  • This interaction may play a significant role in transcription regulation and nucleosome assembly.

More Related Videos

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists10:51

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists

Published on: November 15, 2013

RNA-Associated Chromatin DNA-DNA Interaction Method11:01

RNA-Associated Chromatin DNA-DNA Interaction Method

Published on: April 30, 2026

Related Concept Videos

Heterochromatin02:38

Heterochromatin

The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions that take up more dye are called heterochromatin. Heterochromatin is further classified into two forms – constitutive heterochromatin and facultative heterochromatin.
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...
Heterochromatin02:38

Heterochromatin

The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions that take up more dye are called heterochromatin. Heterochromatin is further classified into two forms – constitutive heterochromatin and facultative heterochromatin.
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...
Euchromatin01:01

Euchromatin

The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

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,...
Inheritance of Chromatin Structures03:17

Inheritance of Chromatin Structures

Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying DNA...
Catenins01:23

Catenins

Catenins are characterized by multiple binding domains and dynamic structures that allow them to function as linker proteins in cell junction complexes. All catenins, except α-catenin, contain a characteristic protein sequence called the armadillo repeat and are therefore also called armadillo proteins.
Catenins in Cell Junctions
Catenins bind to cell adhesion molecules such as cadherins and link them to different cytoskeletal proteins depending on the type of cell junction. At the adherens...