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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...
GPCRs Regulate Adenylyl Cylase Activity01:09

GPCRs Regulate Adenylyl Cylase Activity

Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Amplifying Signals via Second Messengers01:15

Amplifying Signals via Second Messengers

Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
G Protein-coupled Receptors01:15

G Protein-coupled Receptors

G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
Interactions Between Signaling Pathways01:19

Interactions Between Signaling Pathways

Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Covalently Linked Protein Regulators02:04

Covalently Linked Protein Regulators

Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.

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Related Experiment Video

Updated: Jul 6, 2026

A Mass Spectrometry-Based Approach to Identify Phosphoprotein Phosphatases and their Interactors
10:17

A Mass Spectrometry-Based Approach to Identify Phosphoprotein Phosphatases and their Interactors

Published on: April 29, 2022

Progesterone receptor phosphorylation complexities in defining a functional role.

G S Takimoto1, K B Horwitz

  • 1Glenn S. Takimoto and Kathryn B. Horiwitz are at the Division of Endocrinology, University of Colorado Health Sciences Center, Denver, CO 80262, USA.

Trends in Endocrinology and Metabolism: TEM
|January 1, 1993
PubMed
Summary

Progesterone receptors (PRs) undergo complex, multi-stage phosphorylation after ligand binding. The functional importance of this progressive phosphorylation cascade is not yet understood.

Related Experiment Videos

Last Updated: Jul 6, 2026

A Mass Spectrometry-Based Approach to Identify Phosphoprotein Phosphatases and their Interactors
10:17

A Mass Spectrometry-Based Approach to Identify Phosphoprotein Phosphatases and their Interactors

Published on: April 29, 2022

Area of Science:

  • Molecular biology
  • Cellular signaling
  • Endocrinology

Background:

  • Steroid receptors are known phosphoproteins.
  • Progesterone receptors (PRs) exhibit hyperphosphorylation upon ligand engagement.
  • PR phosphorylation is a complex process involving multiple cellular compartments and serine kinases.

Purpose of the Study:

  • To investigate the emerging model of progressive PR phosphorylation in a three-stage cascade.
  • To clarify the functional significance of PR phosphorylation cascades.

Main Methods:

  • The study focuses on the phosphorylation status of progesterone receptors.
  • Analysis involves understanding cellular compartments and serine kinase involvement.
  • A progressive, three-stage phosphorylation cascade model is being explored.

Main Results:

  • Progesterone receptors (PRs) are confirmed to be phosphoproteins.
  • Ligand binding induces hyperphosphorylation of PRs.
  • A progressive, three-stage phosphorylation cascade model for PRs is emerging.

Conclusions:

  • While a progressive phosphorylation cascade for PRs is proposed, its functional significance remains to be elucidated.
  • Further research is needed to understand the biological role of PR phosphorylation stages.