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Related Concept Videos

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...
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...
What are Second Messengers?01:12

What are Second Messengers?

Because many receptor binding ligands are hydrophilic, they do not cross the cell membrane and thus their message must be relayed to a second messenger on the inside. There are several second messenger pathways, each with their own way of relaying information. G-protein coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol path is active when the receptor induces phospholipase C to hydrolyze the phospholipid,...
What are Second Messengers?01:12

What are Second Messengers?

Because many receptor binding ligands are hydrophilic, they do not cross the cell membrane and thus their message must be relayed to a second messenger on the inside. There are several second messenger pathways, each with their own way of relaying information. G-protein coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol path is active when the receptor induces phospholipase C to hydrolyze the phospholipid,...
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...
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...

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Related Experiment Video

Updated: Jul 9, 2026

Absolute Quantitation of Inositol Pyrophosphates by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry
09:22

Absolute Quantitation of Inositol Pyrophosphates by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry

Published on: August 13, 2021

A discrete signaling function for an inositol pyrophosphate.

Philip W Majerus1

  • 1Division of Hematology, Washington University School of Medicine, 660 South Euclid, St. Louis, MO 63110, USA. PHIL@im.wustl.edu

Science'S STKE : Signal Transduction Knowledge Environment
|December 13, 2007
PubMed
Summary

Inositol pyrophosphates (IPs) are crucial for yeast phosphate assimilation. A specific IP(7) acts as a cofactor, inactivating a key kinase to enable phosphate uptake when levels are low.

More Related Videos

Preparation of Quality Inositol Pyrophosphates
10:34

Preparation of Quality Inositol Pyrophosphates

Published on: September 3, 2011

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry
08:07

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Published on: July 26, 2019

Related Experiment Videos

Last Updated: Jul 9, 2026

Absolute Quantitation of Inositol Pyrophosphates by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry
09:22

Absolute Quantitation of Inositol Pyrophosphates by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry

Published on: August 13, 2021

Preparation of Quality Inositol Pyrophosphates
10:34

Preparation of Quality Inositol Pyrophosphates

Published on: September 3, 2011

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry
08:07

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Published on: July 26, 2019

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Yeast Genetics

Background:

  • Inositol pyrophosphates (IPs) are signaling molecules with previously unclear functions.
  • Recent research has identified a specific role for inositol hexaphosphate with one pyrophosphate (IP7) in yeast.
  • The Vip1 gene product in Saccharomyces cerevisiae synthesizes this critical IP7.

Purpose of the Study:

  • To elucidate the function of IP7 in Saccharomyces cerevisiae.
  • To understand the mechanism by which IP7 regulates gene expression related to phosphate assimilation.
  • To identify the molecular targets and pathways influenced by IP7.

Main Methods:

  • Investigated the role of IP7 as a cofactor in enzymatic reactions.
  • Utilized yeast genetics to study the Vip1 gene and its product.
  • Analyzed the effects of IP7 on protein complex inactivation and nuclear translocation of transcription factors.

Main Results:

  • IP7 functions as a cofactor required for the inactivation of the cyclin-cyclin-dependent kinase complex (Pho80, Pho81, and Pho85).
  • Inhibition of this kinase complex leads to the nuclear translocation of the transcription factor Pho4.
  • IP7 accumulates in yeast grown in low-phosphate conditions, driving the expression of phosphate acquisition genes.

Conclusions:

  • IP7 plays a vital role in regulating phosphate homeostasis in yeast.
  • The identified IP7-mediated pathway is essential for adapting to low-phosphate environments.
  • This discovery clarifies a key signaling mechanism in cellular phosphate management.