Which one of the following amino acids is characteristic of and is conserved in response regulator of plant two-component systems?
Aspartic Acid
Plant Two-Component Systems
Plant two-component systems are signaling pathways that allow plants to sense and respond to various environmental stimuli and internal signals, such as hormones, light, and stress. These systems typically involve two main proteins: a histidine kinase (HK) and a response regulator (RR).
Response Regulator Function
The response regulator (RR) is the second component in this system. It receives a phosphoryl group from the histidine kinase. This phosphorylation event activates the response regulator, allowing it to carry out its specific function, often involving gene regulation.
Conserved Amino Acid in Response Regulators
The phosphorylation in most response regulators occurs on a specific, highly conserved amino acid residue. This conserved residue is crucial for the phosphotransfer reaction from the histidine kinase.
The characteristic and conserved amino acid residue that accepts the phosphate group in the response regulator of plant two-component systems is Aspartic Acid.
Aspartic Acid in Signaling
The Aspartic Acid residue is located within a conserved domain of the response regulator protein. When the histidine kinase is activated, it transfers a phosphate group to this specific Aspartic Acid residue. This phosphorylation causes a conformational change in the response regulator, which then allows it to interact with other proteins or DNA, thereby triggering downstream responses.
Therefore, Aspartic Acid is the key amino acid conserved for phosphorylation-dependent activation in response regulators of plant two-component systems.
Summary of Amino Acids
Let's briefly look at the options provided:
- Aspartic Acid: This is the correct answer. It is the characteristic phosphorylated residue in response regulators.
- Glutamic acid: While structurally similar to Aspartic Acid, Glutamic Acid is not typically the site of phosphorylation in standard response regulators.
- Tyrosine: Phosphorylation on Tyrosine is common in receptor tyrosine kinases, particularly in animal signaling, but not the primary site in plant two-component response regulators.
- Histidine: Histidine is the amino acid that gets phosphorylated on the kinase partner (the histidine kinase) in the two-component system, not the response regulator.
Based on the mechanism of plant two-component systems, Aspartic Acid is the amino acid that is characteristic of and conserved in response regulators as the site of phosphorylation.
Important Questions from Cell signaling
In the table below Column A lists ligands and Column B lists classes of receptors
Column A Column B A Serotonin i Binding activates a G-protein which activates or inhibits an enzyme that generates a specific second messenger and opens ion channel B Interferons ii Binding causes receptor monomers to dimerize. Dimeric receptor then interacts with and activates one or more cytosolic tyrosine protein kinases C Glycine iii Binding changes the conformation of the receptor so that specific ions flow through it D Insulin iv Binding leads to activation of intrinsic tyrosine kinase activity Which one is the correct match?
Receptor for which one of the following proteins spans the plasma membrane of target cells but DOES NOT contain intrinsic protein kinase activity?
Which one of the following signaling molecules is NOT a protein or a peptide?
Receptor tyrosine kinases (RTKs) form a large and important class of cell surface receptors whose ligands are soluble or membrane bound protein or peptide hormones. Which of the following statement is INCORRECT?
Nitric oxide (NO) acts as intracellular second messenger by stimulating
