Related Experiment Video

Updated: Jun 2, 2026

Tyramide Signal Amplification for the Immunofluorescent Staining of ZBP1-Dependent Phosphorylation of RIPK3 and MLKL After HSV-1 Infection in Human Cells
09:15

Tyramide Signal Amplification for the Immunofluorescent Staining of ZBP1-Dependent Phosphorylation of RIPK3 and MLKL After HSV-1 Infection in Human Cells

Published on: October 20, 2022

NRIP, a novel calmodulin binding protein, activates calcineurin to dephosphorylate human papillomavirus E2 protein

Szu-Wei Chang1, Yeou-Ping Tsao, Chia-Yi Lin

  • 1Graduate Institute of Microbiology, College of Medicine, National Taiwan University, 7F, No1, Sec. 1, Jen-Ai Rd., Taipei, Taiwan.

Journal of Virology
|May 6, 2011
PubMed

Insights

Nuclear Receptor Interaction Protein (NRIP) binds human papillomavirus 16 E2 protein, stabilizing it. NRIP prevents E2 degradation via calcium/calmodulin and calcineurin, enhancing viral gene expression.

Area of Science:

  • Molecular biology
  • Virology
  • Cellular biology

Background:

  • Nuclear Receptor Interaction Protein (NRIP), also known as DCAF6 or IQWD1, is a previously identified gene.
  • Human Papillomavirus (HPV) infection is a significant global health concern, with the HPV-16 E2 protein playing a crucial role in viral replication and gene expression.

Purpose of the Study:

  • To investigate the interaction between NRIP and HPV-16 E2 protein.
  • To elucidate the mechanism by which NRIP influences HPV-16 E2 protein stability and function.
  • To explore the role of calcium/calmodulin and calcineurin in regulating E2 protein stability.

Main Methods:

  • Co-immunoprecipitation assays to demonstrate in vivo and in vitro complex formation between NRIP and HPV-16 E2.
  • Small interfering RNA (siRNA) mediated knockdown of NRIP to assess its effect on E2 protein levels and gene expression.
  • Analysis of NRIP's interaction with calcium/calmodulin and its effect on E2 ubiquitination and phosphorylation.
  • Investigation of calcineurin activity in the NRIP-E2-calcium/calmodulin complex.

Main Results:

  • NRIP directly binds to the HPV-16 E2 protein through its N-terminal domain interacting with E2's transactivation domain.
  • Full-length NRIP is required to stabilize E2 protein and induce HPV gene expression; NRIP silencing reduces E2 levels and activity.
  • NRIP binds calcium/calmodulin via its IQ domain, decreasing E2 ubiquitination and enhancing E2 protein stability.
  • The NRIP-calcium/calmodulin complex activates calcineurin, leading to E2 dephosphorylation and further stabilization.

Conclusions:

  • NRIP acts as a novel binding partner for HPV-16 E2, significantly enhancing its stability and function.
  • NRIP functions as a molecular scaffold, recruiting E2 and calcium/calmodulin to prevent E2 polyubiquitination and degradation.
  • This NRIP-mediated stabilization of E2 protein is crucial for promoting HPV gene expression and viral replication.

More Related Videos

Monitoring Activation of the Antiviral Pattern Recognition Receptors RIG-I And PKR By Limited Protease Digestion and Native PAGE12:43

Monitoring Activation of the Antiviral Pattern Recognition Receptors RIG-I And PKR By Limited Protease Digestion and Native PAGE

Published on: July 29, 2014

Molecular Modulation by Lentivirus-Delivered Specific shRNAs in Endoplasmic Reticulum Stressed Neurons10:50

Molecular Modulation by Lentivirus-Delivered Specific shRNAs in Endoplasmic Reticulum Stressed Neurons

Published on: April 24, 2021

Related Concept Videos

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,...
Regulation of the Unfolded Protein Response01:31

Regulation of the Unfolded Protein Response

Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
RNA Polymerase II Accessory Proteins02:36

RNA Polymerase II Accessory Proteins

Proteins that regulate transcription can do so either via direct contact with RNA Polymerase or through indirect interactions facilitated by adaptors, mediators, histone-modifying proteins, and nucleosome remodelers. Direct interactions to activate transcription is seen in bacteria as well as in some eukaryotic genes. In these cases, upstream activation sequences are adjacent to the promoters, and the activator proteins interact directly with the transcriptional machinery. For example, in...
Initiation of Translation02:33

Initiation of Translation

Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
Eukaryotic RNA Polymerases00:58

Eukaryotic RNA Polymerases

RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...