Related Experiment Video

Updated: Oct 7, 2026

Co-immunoprecipitation Assay for Studying Functional Interactions Between Receptors and Enzymes
09:40

Co-immunoprecipitation Assay for Studying Functional Interactions Between Receptors and Enzymes

Published on: September 28, 2018

Inhibition of the catalytic activity of cell adhesion kinase beta by protein-tyrosine phosphatase-PEST-mediated

P D Lyons1, J M Dunty, E M Schaefer

  • 1Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA.

The Journal of Biological Chemistry
|May 5, 2001
PubMed

Insights

Protein-tyrosine phosphatase (PTP)-PEST dephosphorylates and inhibits cell adhesion kinase beta (CAKbeta), a key regulator of focal adhesions. This study identifies CAKbeta as a PTP-PEST substrate, impacting cell signaling pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Protein-tyrosine phosphatase (PTP)-PEST dephosphorylates focal adhesion proteins.
  • Protein-tyrosine kinases like focal adhesion kinase (FAK) and cell adhesion kinase beta (CAKbeta) phosphorylate these proteins.

Purpose of the Study:

  • To investigate whether CAKbeta and FAK are substrates of PTP-PEST.
  • To elucidate the regulatory role of PTP-PEST in CAKbeta and FAK signaling pathways.

Main Methods:

  • Substrate-trapping assays in mammalian cells.
  • Overexpression of PTP-PEST and analysis of CAKbeta and FAK activity.
  • Immunofluorescence to determine cellular localization of endogenous proteins.

Main Results:

  • CAKbeta is a substrate of PTP-PEST, with dephosphorylation occurring at key regulatory tyrosine residues (Tyr402, Tyr579, Tyr580).
  • PTP-PEST dephosphorylation significantly inhibits CAKbeta kinase activity.
  • PTP-PEST reduces tyrosine phosphorylation of paxillin, an event enhanced by CAKbeta.
  • FAK is a poor substrate for PTP-PEST, with no significant effect on its kinase activity.
  • Endogenous PTP-PEST and CAKbeta colocalize in epithelial and smooth muscle cells.

Conclusions:

  • CAKbeta is a direct substrate of PTP-PEST, and PTP-PEST negatively regulates CAKbeta kinase activity.
  • PTP-PEST plays a significant role in modulating CAKbeta-mediated signaling pathways.
  • FAK is not a significant substrate for PTP-PEST, suggesting pathway-specific regulation.

More Related Videos

Assessing Cellular Target Engagement by SHP2 (PTPN11) Phosphatase Inhibitors08:45

Assessing Cellular Target Engagement by SHP2 (PTPN11) Phosphatase Inhibitors

Published on: July 17, 2020

Development and Application of Rapamycin-regulated Tyrosine Phosphatases06:56

Development and Application of Rapamycin-regulated Tyrosine Phosphatases

Published on: September 6, 2024

Related Concept Videos

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...
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...
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...
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...
cAMP-dependent Protein Kinase Pathways01:25

cAMP-dependent Protein Kinase Pathways

Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...