Question

Which of the following proteins is a major constituent of synaptic ribbons? a. Retinol dehydrogenase b. Melanin c. Ribeye d. RGS/G \(\beta 5\) e. Bestrophin

Short answer

Answer: Ribeye

Step-by-step solution

Understand synaptic ribbons

Synaptic ribbons are electron-dense structures found at the active zones of certain synapses, particularly in sensory neurons, such as photoreceptors and hair cells. These structures play an important role in the release of neurotransmitters to facilitate communication between neurons.

Review the list of proteins

The given list of proteins includes: a. Retinol dehydrogenase b. Melanin c. Ribeye d. RGS/Gß5 e. Bestrophin

Eliminate irrelevant proteins

a. Retinol dehydrogenase: an enzyme involved in the metabolism of retinoids, not related to synaptic ribbons. b. Melanin: a pigment responsible for skin and hair color, not related to synaptic ribbons. d. RGS/Gß5: a complex that regulates G protein signaling, not directly related to synaptic ribbons. e. Bestrophin: a calcium-activated chloride channel protein, not directly related to synaptic ribbons.

Identify the correct protein

c. Ribeye: Ribeye is a major protein component of synaptic ribbons. It is essential for the formation and function of these structures and is found at the core of synaptic ribbons.

Conclusion

The major constituent of synaptic ribbons is Ribeye (c).

Key concepts

Synaptic Ribbons

Synaptic ribbons are fascinating structures found in the specialized synapses of sensory neurons. These structures are particularly prevalent in cells such as photoreceptors in the eyes and hair cells in the ears. They are located at the active zones of synapses and appear as dense, ribbon-like formations under an electron microscope. The primary function of synaptic ribbons is to enable rapid and continuous neurotransmitter release, which is crucial for the constant relay of environmental signals to the brain.

• Function and Structure: These ribbons hold a reserve of synaptic vesicles within close proximity to the cell membrane, ensuring quick and sustained neurotransmitter release.
• Key Protein: Ribeye is the major protein component of these structures, driving both their formation and function.

In summary, synaptic ribbons are integral to the efficient communication between sensory neurons and their target cells.

Neurotransmitter Release

Neurotransmitter release is a fundamental process in nerve cell communication. It involves the transfer of chemical signals from one neuron to another or to a target cell, such as a muscle or gland cell. This process occurs at the synapse, the junction where neurons connect and communicate.

• Mechanism: Neurotransmitters are stored in small vesicles within the neuron. Upon an electrical signal arriving at the synapse, these vesicles fuse with the cell membrane and release their contents into the synaptic cleft.
• Role of Synaptic Ribbons: In sensory neurons, synaptic ribbons ensure a steady supply of vesicles ready for release, allowing for rapid and continuous neurotransmitter output.

This continuous release is essential for sensory processes, allowing us to see, hear, and respond to our surroundings efficiently.

Sensory Neurons

Sensory neurons are specialized nerve cells responsible for converting external stimuli from the environment into internal electrical impulses. These neurons are vital for processing sensory information, including sight, hearing, touch, taste, and smell.

• Types: Examples include photoreceptors in the eyes and hair cells in the ears, each adapted to detect specific kinds of sensory input.
• Connection to Synaptic Ribbons: Sensory neurons often have synaptic ribbons, which facilitate the reliable and swift communication of sensory information to the brain.

The efficient functioning of sensory neurons is crucial for our perception of the world, enabling us to react and adapt to changing environments.