Activation loop phosphorylation of the atypical MAP kinases ERK3 and ERK4 is required for binding, activation and

Related Experiment Video

Updated: Jul 2, 2026

Assaying Protein Kinase Activity with Radiolabeled ATP
08:05

Assaying Protein Kinase Activity with Radiolabeled ATP

Published on: May 26, 2017

Paul Déléris1, Justine Rousseau, Philippe Coulombe

  • 1Institut de Recherche en Immunologie et Cancérologie, Montreal, Quebec, Canada.

Journal of Cellular Physiology
|August 23, 2008
PubMed

Insights

Atypical mitogen-activated protein (MAP) kinases ERK3 and ERK4 are phosphorylated in their activation loop, which enhances their catalytic activity and promotes complex formation with MK5. This regulation differs from classical MAP kinases.

Area of Science:

  • Cellular signaling
  • Molecular biology
  • Biochemistry

Background:

  • Mitogen-activated protein (MAP) kinases regulate cellular processes via activation loop phosphorylation.
  • Classical MAP kinases (ERK1/2, JNK, p38, ERK5) have a dual phosphorylation motif (Thr-Xxx-Tyr) in their activation loop.
  • Atypical MAP kinases ERK3 and ERK4 possess a unique single phosphorylation site (Ser-Glu-Gly) in their activation loop, with less understood regulation.

Purpose of the Study:

  • To investigate the in vivo phosphorylation and functional regulation of atypical MAP kinases ERK3 and ERK4.
  • To compare the activation loop phosphorylation mechanisms of atypical ERK3/ERK4 with classical MAP kinases.
  • To elucidate the role of activation loop phosphorylation in ERK3/ERK4 catalytic activity and complex formation.

Main Methods:

  • In vivo phosphorylation analysis of ERK3 and ERK4.
  • Investigation of upstream kinase activity and substrate interactions.
  • Assessment of catalytic activity and complex formation with MAP kinase-activated protein kinase 5 (MK5).

Main Results:

  • ERK3 and ERK4 undergo in vivo activation loop phosphorylation, partly mediated in trans by an upstream kinase.
  • Unlike classical MAP kinases, ERK3/ERK4 phosphorylation is present in resting cells and not significantly altered by mitogenic or stress stimuli.
  • Activation loop phosphorylation of ERK3/ERK4 enhances their intrinsic catalytic activity and is essential for stable complex formation with MK5, facilitating cytoplasmic redistribution.

Conclusions:

  • Activation loop phosphorylation is crucial for regulating the function of atypical MAP kinases ERK3 and ERK4.
  • ERK3/ERK4 regulation via activation loop phosphorylation differs significantly from classical MAP kinases.
  • Phosphorylation-dependent complex formation with MK5 is a key aspect of ERK3/ERK4 signaling.

More Related Videos

Subcellular Fractionation for ERK Activation Upon Mitochondrial-derived Peptide Treatment07:55

Subcellular Fractionation for ERK Activation Upon Mitochondrial-derived Peptide Treatment

Published on: September 25, 2017

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting10:08

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting

Published on: December 9, 2022

Related Concept Videos

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...
PI3K/mTOR/AKT Signaling Pathway01:22

PI3K/mTOR/AKT Signaling Pathway

The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a rapamycin-insensitive companion...
Microtubule Associated Proteins (MAPs)01:42

Microtubule Associated Proteins (MAPs)

Microtubule function and architecture are regulated by an array of specialized proteins called microtubule-associated proteins or MAPs. These proteins are widespread across different organisms and have conserved protein motifs, like the multi-TOG domain for tubulin binding found in the CLASP family of MAPs. Some MAPs are lineage-specific based on their conserved domains. Their functions depend upon the cytoskeletal architecture and cell type they are located within. In-plant cells, a specific...
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,...
Receptor Tyrosine Kinases01:26

Receptor Tyrosine Kinases

Receptor tyrosine kinases or RTKs are membrane-bound receptors that phosphorylate specific tyrosine on protein substrates. RTKs regulate cellular growth, differentiation, survival, and migration. They contain an extracellular ligand binding domain, a transmembrane domain, and a cytosolic tail with intrinsic kinase activity. Several extracellular signaling molecules activate RTKs in one or more ways and relay the signal downstream. Ligands such as platelet-derived growth factor (PDGF) or...
M-Cdk Drives Transition Into Mitosis02:15

M-Cdk Drives Transition Into Mitosis

Checkpoints throughout the cell cycle serve as safeguards and gatekeepers, allowing the cell cycle to progress in favorable conditions and slow or halt it in problematic ones. This regulation is known as the cell cycle control system.
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...