Plant nodulation genes encode proteins with receptor‐like‐features. Following are the list of some nodulation proteins (Column X) and their possible domain characteristics (Column Y): Column X Column Y A. i. B. ii. C. iii.Entry receptor Extracellular leucine-rich repeat domains in a large N-terminal segment and the cytoplasmic portion having kinase domains. Signalling receptor Extracellular LysM domains and the cytoplasmic kinase domain's Symbiosis receptor kinase Extracellular LysM domains but lacks the kinase features in the cytoplasmic portion
Which of the following is the correct match?
A – ii, B – iii, C – i
Understanding Plant Nodulation Receptor Domains
Plant nodulation is a complex process involving communication between plants and nitrogen-fixing bacteria, leading to the formation of nodules. This communication relies on specific receptor proteins on the plant cell surface that recognize bacterial signals, such as Nod factors.
These receptor proteins have distinct structural features, known as domains, which are responsible for signal recognition, transmission across the membrane, and initiating downstream responses within the cell.
Let's look at the list of nodulation proteins and their potential domain characteristics provided in the question:
- Column X: A. Entry receptor, B. Signalling receptor, C. Symbiosis receptor kinase
- Column Y: i. Extracellular leucine-rich repeat (LRR) domains and cytoplasmic kinase domains. ii. Extracellular LysM domains and cytoplasmic kinase domains. iii. Extracellular LysM domains but lacks kinase features in the cytoplasmic portion.
We need to match the receptor types in Column X with the correct domain characteristics in Column Y based on the known structures and functions of these receptors in plant nodulation pathways.
Matching Nodulation Receptors and Domains
Based on the typical characteristics of nodulation receptors:
-
Entry receptor (A): The initial recognition of Nod factors by the plant is often mediated by LysM domain-containing receptors. Some of these receptors are LysM receptor kinases (LysM-RKs), possessing both extracellular LysM domains for ligand binding and a cytoplasmic kinase domain for signal transduction. An example is NFR1 in many legumes.
This aligns with characteristic (ii): Extracellular LysM domains and the cytoplasmic kinase domain. -
Signalling receptor (B): Other receptors involved in the early signalling cascade also contain LysM domains but may lack a functional kinase domain, acting as receptor-like proteins (RLPs) or receptor-like kinases (RLKs) that require association with other kinases for signalling. An example is NFR5, which has LysM domains but lacks kinase activity and partners with NFR1.
This aligns with characteristic (iii): Extracellular LysM domains but lacks the kinase features in the cytoplasmic portion. -
Symbiosis receptor kinase (C): A key downstream receptor involved in initiating the complex symbiotic program is the Symbiosis Receptor Kinase (SYMRK). This receptor has a distinct structure featuring extracellular Leucine-Rich Repeat (LRR) domains, which are often involved in protein-protein interactions or recognition of different signals, and a cytoplasmic kinase domain essential for activating downstream signalling pathways.
This aligns with characteristic (i): Extracellular leucine-rich repeat domains in a large N-terminal segment and the cytoplasmic portion having kinase domains.
Confirming the Correct Match
Putting the matches together based on our understanding:
- A (Entry receptor) matches with (ii) (LysM + kinase)
- B (Signalling receptor) matches with (iii) (LysM + no kinase)
- C (Symbiosis receptor kinase) matches with (i) (LRR + kinase)
This gives us the combination: A – ii, B – iii, C – i.
Comparing this to the provided options, the correct match is Option 2: A – ii, B – iii, C – i.
Important Questions from Cellular communication
In a neuron, proteins and membranes are primarily synthesized in the cell body. These materials must be transported down the axon to the synaptic region using microtubules in an anterograde fashion. Such axonal transport is directed by
Acetylcholine is a potent neurotransmitter, which is released from the neurons. After release they diffuse across the synaptic cleft and combine with nicotinic acetylcholine receptor molecules in the membrane of the postsynaptic cell. The interaction of acetylcholine with the nicotinic acetylcholine receptor produces large transient increase in the permeability of the membrane to specialized ions resulting in signal transduction for nerve impulse. Acetylcholine receptor is a
Column X represents the type of junctions and column Y represents the proteins associated with the junctions.
Column X
Column Y
A.
Anchoring junction
i.
Claudins
B.
Occluding junction
ii.
Delta-Notch
C.
Channel-forming junction
iii.
Desmoglein
D.
Signal-relaying junction
iv.
Connexin
Which one of the following options is a correct match between terms of Columns X and Y?
Bacteria employ various mechanisms to invade or enter host cells, which are either phagocytic or non-phagocytic in nature. Given below are some of the mechanisms which are generally used for carrying out this process.
A. Some bacteria express a protein called invasin that is recognized by host-cell β1 integrins.
B. Actin polymerization along with assembly of clathrin coat results in the internalization of bacteria by zipper mechanism.
C. Some bacteria, including Salmonella enterica, use trigger mechanism to inject a set of effector molecules in the cytosol through type III secretion system.
D. Some bacteria attach to host cell surface receptors inducing local elevation of Ca2+ in cell cytosol, leading to the fusion of lysosomes with bacteria containing plasma membrane vesicles.
Which one of the following represents the combination of correct mechanisms for invading non-phagocytic cells?
In C. elegans, PAR proteins segregate at the cell cortex in the zygote to establish cell polarity. This is dependent on the regulation of the cortical actin cytoskeleton by RhoA. An investigator sought to directly inhibit actin polymerization to analyze the impact of this inhibition on PAR protein localization. Which one of the following chemicals would be the most suitable?
