Related Experiment Video
Updated: Apr 28, 2026
05:47
Phosphoproteomic Strategy for Profiling Osmotic Stress Signaling in Arabidopsis
Published on: June 25, 2020
4.5K
Structural and functional basis for starch binding in the SnRK1 subunits AKINβ2 and AKINβγ
Alejandra Avila-Castañeda1, Natalia Gutiérrez-Granados1, Ana Ruiz-Gayosso1
1Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México México City, México.
Frontiers in Plant Science
|June 7, 2014
Summary
Plant proteins with starch-binding domains (SBDs) interact with starch, influencing SnRK1 kinase activity. AKINβγ binds starch in chloroplasts, inhibiting activity, while AKINβ2 shows different binding affinities.
Area of Science:
- Biochemistry
- Plant Molecular Biology
- Enzymology
Background:
- Specialized carbohydrate-binding domains, Starch-Binding Domain (SBD) and Glycogen Binding Domain (GBD), are key in carbohydrate metabolism.
- These domains are found in regulatory subunits of the AMPK/SNF1/SnRK1 complex, crucial for energy sensing.
- In Arabidopsis thaliana, AKINβ2 and AKINβγ possess SBDs, suggesting roles in starch metabolism.
Purpose of the Study:
- To compare the structure and function of plant SBDs (AKINβ2, AKINβγ) with a known animal GBD (rat AMPKβ1).
- To investigate the binding capabilities of plant SBDs to starch and its components.
- To elucidate the impact of starch binding on SnRK1 kinase activity and subunit association.
Main Methods:
- Structural comparison of plant SBDs and rat AMPKβ1 GBD.
- In vitro binding assays using starch, amylose/amylopectin mixtures, and purified proteins.
- Enzyme activity assays measuring SnRK1 kinase activity with and without starch or A/A.
- Immunolocalization to determine the cellular localization of AKINβγ.
Main Results:
- Plant SBDs (AKINβ2, AKINβγ) share structural topology with rat AMPKβ1 GBD, with conserved carbohydrate-interaction residues.
- AKINβγ and AKINβ2 SBDs bind starch, with differential affinity for amylose/amylopectin mixtures.
- AKINβγ localizes to the chloroplast, the site of starch synthesis and storage.
- Starch binding inhibits SnRK1 kinase activity by 85%, while A/A mixture has no effect.
- Only catalytic subunits (AKIN10, AKIN11) and AKINβγ associate with starch/A/A complexes, suggesting specific subunit involvement.
Conclusions:
- Plant SBDs are structurally conserved and functionally capable of binding starch.
- AKINβγ's chloroplast localization highlights its role in starch metabolism regulation.
- Starch binding inactivates SnRK1 kinase activity, mediated by specific subunit interactions.
- A dimer of catalytic subunits with AKINβγ may remain active when bound to A/A but is inactivated by starch.
More Related Videos
09:07Concanavalin A-Based Sedimentation Assay to Measure Substrate Binding of Glucan Phosphatases
Published on: December 23, 2022
1.7K
05:22Transverse Sectioning of Mature Rice Oryza sativa L. Kernels for Scanning Electron Microscopy Imaging Using Pipette Tips as Immobilization Support
Published on: January 25, 2022
3.6K
Related Concept Videos
00:49Ligand Binding and Linkage
4.4K
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...
4.4K
01:56Structural Protein Function
2.6K
2.6K
01:56Structural Protein Function
28.8K
Structural proteins are a category of proteins responsible for functions ranging from cell shape and movement to providing support to major structures such as bones, cartilage, hair, and muscles. This group includes proteins such as collagen, actin, myosin, and keratin.
Collagen, the most abundant protein in mammals, is found throughout the body. In connective tissue, such as skin, ligaments, and tendons, it provides tensile strength and elasticity. In bones and teeth, it mineralizes to...
Collagen, the most abundant protein in mammals, is found throughout the body. In connective tissue, such as skin, ligaments, and tendons, it provides tensile strength and elasticity. In bones and teeth, it mineralizes to...
28.8K
01:19Allosteric Proteins-ATCase
4.8K
Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis...
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis...
4.8K
01:57Protein Complexes with Interchangeable Parts
2.1K
Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order...
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order...
2.1K
01:30Assembly of Signaling Complexes
4.7K
Multiprotein signaling complexes are formed in a dynamic process involving protein-protein interactions at the cytoplasmic domain of transmembrane receptors or enzymatic and non-enzymatic proteins associated with the receptor. These complexes ensure the activation and propagation of intracellular signals that regulate cell functions.
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
4.7K