Linking structure to function: Recent lessons from inositol 1,4,5-trisphosphate receptor mutagenesis.
David I Yule1, Matthew J Betzenhauser, Suresh K Joseph
1Department of Pharmacology and Physiology, University of Rochester, NY, United States. David_Yule@urmc.rochester.edu
Cell Calcium
|June 1, 2010
Summary
Mutagenesis studies reveal key aspects of the inositol 1,4,5 trisphosphate receptor (InsP3R). Research defines InsP3 binding sites and channel function, aiding understanding of in vivo regulation and gating mechanisms.
Area of Science:
- Molecular biology
- Cell signaling
- Biochemistry
Background:
- The inositol 1,4,5 trisphosphate receptor (InsP3R) is crucial for intracellular calcium signaling.
- Mutagenesis studies have previously identified key domains for InsP3 binding and channel function.
Purpose of the Study:
- To evaluate recent mutagenesis studies on InsP3R.
- To investigate structural requirements for in vivo modulation by regulatory factors.
- To review structural aspects of the InsP3R channel domain involved in conduction and gating.
Main Methods:
- Site-directed mutagenesis of InsP3R cDNA.
- Analysis of InsP3 binding site constituents.
- Investigation of C-terminal membrane-spanning regions for channel formation.
- Evaluation of structural requirements in the channel domain.
Main Results:
- Mutagenesis has defined the N-terminus for InsP3 binding.
- The C-terminal domain is critical for channel formation, targeting, and function.
- Recent studies elucidate residues involved in in vivo regulation.
- Structural requirements for conduction and gating within the channel domain are being defined.
Conclusions:
- Mutagenesis remains a powerful tool for dissecting InsP3R structure and function.
- Understanding InsP3R regulation and gating is advancing through detailed molecular studies.
- Further research will refine the structural basis of InsP3R channel activity.
Related Concept Videos
01:42Phosphoinositides 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...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
00:49Ligand Binding and Linkage
Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence the...
02:04Covalently 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.
These groups modify specific amino acids in a protein.
02:54Protein 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...
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
01:11IP3/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...
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...