Related Experiment Video

Updated: Aug 9, 2026

Rab10 Phosphorylation Detection by LRRK2 Activity Using SDS-PAGE with a Phosphate-binding Tag
08:55

Rab10 Phosphorylation Detection by LRRK2 Activity Using SDS-PAGE with a Phosphate-binding Tag

Published on: December 14, 2017

S100beta inhibits the phosphorylation of the L-MAG cytoplasmic domain by PKA

P Kursula1, V P Lehto, A M Heape

  • 1Department of Pathology, University of Oulu, Oulu, Finland. petri.kursula@oulu.fi

Brain Research. Molecular Brain Research
|April 14, 2000
PubMed

Insights

The myelin-associated glycoprotein (MAG) is phosphorylated by protein kinase A (PKA), with S100beta modulating this interaction. This suggests L-MAG plays a role in glial cell signaling.

Area of Science:

  • Neuroscience
  • Cell Biology
  • Biochemistry

Background:

  • Myelin-associated glycoprotein (MAG) is a cell adhesion molecule produced by myelinating glial cells.
  • MAG exists in two isoforms, differing in their cytoplasmic domains.
  • The L-MAG isoform contains a specific domain not present in the other isoform.

Purpose of the Study:

  • To investigate the in vitro phosphorylation of recombinant rat MAG cytoplasmic domains.
  • To identify kinases that phosphorylate the MAG cytoplasmic domains.
  • To explore the functional significance of the interaction between L-MAG and S100beta.

Main Methods:

  • In vitro kinase assays were performed using recombinant rat MAG cytoplasmic domains.
  • Three specific kinases with consensus phosphorylation sequences in the MAG domain were tested.
  • The effect of S100beta on L-MAG phosphorylation by protein kinase A (PKA) was assessed.

Main Results:

  • Protein kinase A (PKA) was found to phosphorylate the L-MAG-specific cytoplasmic domain.
  • The presence of S100beta decreased the phosphorylation of the L-MAG cytoplasmic domain by PKA.
  • This indicates a functional interaction between L-MAG and S100beta.

Conclusions:

  • L-MAG phosphorylation by PKA is modulated by S100beta.
  • The interaction between L-MAG and S100beta has functional significance.
  • L-MAG may be involved in signaling pathways within myelinating glial cells.

More Related Videos

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein11:23

Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein

Published on: June 30, 2019

Related Concept Videos

Protein Kinases and Phosphatases02:54

Protein Kinases and Phosphatases

Proteins undergo chemical modifications that trigger changes in the charge, structure, and conformation of the proteins. Phosphorylation, acetylation, glycosylation, nitrosylation, ubiquitination, lipidation, methylation, and proteolysis are various protein modifications that regulate protein activity. Such modifications are usually enzyme-driven.
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
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...
Amplifying Signals via Enzymatic Cascade01:22

Amplifying Signals via Enzymatic Cascade

When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze the...
The JAK-STAT Signaling Pathway01:20

The JAK-STAT Signaling Pathway

Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as  SH2...
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...
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,...