Ligand Gated Ion Channel Receptor Flashcards
What is the structural composition of a ligand-gated ion channel receptor (LGICR)?
A ligand-gated ion channel receptor is made up of five proteins, forming a structure known as a pentamer.
How are the amino acids within the LGICR structured in relation to the cell membrane?
The amino acids have both hydrophilic and hydrophobic parts. The hydrophobic portions remain embedded within the lipid layer of the cell membrane, while the hydrophilic parts are located in the phosphate head area of the membrane.
How many transmembrane domains do ligand-gated ion channel receptors have?
Ligand-gated ion channel receptors have four transmembrane domains.
What role do acetylcholine molecules play in the functioning of the LGICR?
Two acetylcholine molecules bind to the alpha protein parts of the pentamer, activating the LGICR and causing the channel to open.
What effect does the stimulation of nicotinic acetylcholine receptors have on skeletal muscles?
Stimulation of nicotinic acetylcholine receptors in skeletal muscles leads to rapid muscle contraction.
How can damage to the LGICR affect muscle function, specifically in the case of Myasthenia Gravis?
In Myasthenia Gravis, lymphocytes and macrophages attack the Alpha 1 Receptors, leading to muscle weakness, which can manifest as symptoms like droopy eyes or difficulty moving.
Can you provide examples of other ligand-gated ion channel receptors and their functions?
Examples of ligand-gated ion channel receptors include glycine receptors and GABA(a) receptors. These receptors facilitate chloride ion influx, which leads to hyperpolarization of the neuron, contrasting with the sodium ion influx that causes depolarization.
How do G protein-coupled receptors (GPCRs) differ from ligand-gated ion channel receptors in terms of response time?
G protein-coupled receptors (GPCRs) are slower to respond compared to ligand-gated ion channel receptors because they require the activation of muscarinic receptors via G proteins to initiate enzyme activity.
What is the significance of the pentamer structure in ligand-gated ion channels?
The pentamer structure is crucial as it allows for the assembly of multiple protein subunits, which create a channel that can selectively open and close in response to ligand binding, enabling precise control of ion flow across the membrane.
Which specific part of the LGICR do acetylcholine molecules bind to?
Acetylcholine molecules bind to the alpha protein parts of the pentamer in the ligand-gated ion channel receptor.
What happens to muscle function when nicotinic acetylcholine receptors are compromised?
When nicotinic acetylcholine receptors are compromised, as in conditions like Myasthenia Gravis, it leads to reduced muscle contraction and increased muscle weakness.
What is the primary ion that glycine receptors and GABA(a) receptors allow to enter the cell, and what is the effect of this influx?
Glycine receptors and GABA(a) receptors primarily allow chloride ions to enter the cell, resulting in hyperpolarization of the neuron, which decreases the likelihood of action potential generation.
In contrast to LGICRs, what is the general mechanism through which GPCRs operate?
GPCRs operate by activating G proteins, which then activate intracellular enzymes, leading to slower and more complex signalling cascades compared to the direct and rapid response of ligand-gated ion channels.
How do the hydrophobic and hydrophilic regions of the amino acids contribute to the function of LGICRs?
The hydrophobic regions anchor the LGICR within the lipid bilayer of the cell membrane, while the hydrophilic regions interact with the aqueous environment, facilitating the binding of ligands and the opening of the ion channel.
What are some clinical manifestations of Myasthenia Gravis related to muscle weakness?
Clinical manifestations of Myasthenia Gravis related to muscle weakness can include droopy eyelids (ptosis), difficulty swallowing, and overall muscle fatigue, particularly after periods of activity.
