Related Experiment Video

Updated: Jul 15, 2026

In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes
10:05

In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes

Published on: August 13, 2012

Structure of calcineurin in complex with PVIVIT peptide: portrait of a low-affinity signalling interaction

Huiming Li1, Lan Zhang, Anjana Rao

  • 1The CBR Institute, for Biomedical Research, 200 Longwood Avenue, Boston, MA 02115, USA.

Journal of Molecular Biology
|May 15, 2007
PubMed

Insights

Calcineurin binds substrates via a PxIxIT motif, adding to its beta-sheet. Variations in this sequence fine-tune binding affinity for diverse cellular functions.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Cell Biology

Background:

  • Calcineurin is a crucial protein phosphatase regulating eukaryotic cell pathways.
  • Substrate recognition by calcineurin, including the transcription factor NFAT, relies on docking at a specific PxIxIT consensus site.

Purpose of the Study:

  • To elucidate the structural basis of calcineurin's recognition of the PxIxIT sequence.
  • To understand how sequence variations within the PxIxIT motif affect calcineurin-substrate interactions.

Main Methods:

  • Structural analysis of calcineurin-peptide interactions.
  • High-affinity peptide ligand binding assays.
  • Investigation of PxIxIT sequence variations and their impact on binding affinity (K(d)).

Main Results:

  • The high-affinity peptide ligand PVIVIT binds as a beta-strand to the calcineurin beta-sheet.
  • Short peptide segments with the PxIxIT motif are sufficient for calcineurin-substrate docking.
  • Sequence variations within the PxIxIT core modulate the dissociation constant (K(d)) between 1 microM and 1 mM.

Conclusions:

  • Calcineurin's substrate recognition is primarily mediated by the PxIxIT sequence.
  • The adaptability of calcineurin to various substrates is facilitated by this sequence-specific recognition and the ability to fine-tune binding affinity.
  • Understanding this interaction is key to comprehending diverse cellular signaling pathways regulated by calcineurin.

More Related Videos

Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale10:50

Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale

Published on: March 14, 2019

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,...
Assembly of Signaling Complexes01:30

Assembly of Signaling Complexes

Multiprotein signaling complexes are formed in a dynamic process involving protein-protein interactions at the cytoplasmic domain of transmembrane receptors or enzymatic and non-enzymatic proteins associated with the receptor. These complexes ensure the activation and propagation of intracellular signals that regulate cell functions.
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
IP3/DAG Signaling Pathway01:11

IP3/DAG Signaling Pathway

Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the  phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
Non-Canonical Wnt Signaling Pathways01:41

Non-Canonical Wnt Signaling Pathways

Wnt is a zygotic effect gene that is expressed during very early embryonic development. It regulates various processes in animals starting from early development through the adult stage, such as organogenesis in the embryo and maintenance of neuronal and blood stem cells. Wnt proteins can induce a wide variety of intracellular pathways depending upon the specific abilities of different Wnt ligands to form a complex with shared and cognate receptors in the presence of different co-receptors. The...
Phosphoinositides and PIPs01:42

Phosphoinositides and PIPs

Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Protein-protein Interfaces02:04

Protein-protein Interfaces

Many proteins form complexes to carry out their functions, making protein-protein interactions (PPIs) essential for an organism's survival. Most PPIs are stabilized by numerous weak noncovalent chemical forces. The physical shape of the interfaces determines the way two proteins interact. Many globular proteins have closely-matching shapes on their surfaces, which form a large number of weak bonds. Additionally, many PPIs occur between two helices or between a surface cleft and a polypeptide...