The role of protein synthesis in engram consolidation
It has been proven that any learning process is accompanied by the production of specific polypeptides and special brain-specific proteins. These protein synthesis processes are completely ineffective shortly after information intake, when the short-term memory phase is active. However, later on, the synthesis of new molecules becomes critical for the formation of long-term memory.
It is precisely thanks to proteins that engram consolidation takes place—the structural and functional fixation of the memory trace in the nervous system.
The effect of blockers on memory processes
The involvement of proteins in memory mechanisms was reliably confirmed in experiments using protein synthesis inhibitors (blockers). These substances made it possible to prove that the formation of long-term memory is impossible without the creation of new protein molecules.
Main blockers and their effects:
- Puromycin. Its mechanism of action consists in the premature release of the nascent protein molecule from ribosomes. If administered to already trained animals, the retention time of the skill is reduced. If administered before training, short-term memory remains intact and the rate of acquiring new skills does not change, but the process of their consolidation is severely disrupted.
- Cycloheximide (causes translation blockade on ribosomes) and actinomycin D (blocks transcription). These substances effectively suppress previously acquired skills. If protein synthesis inhibition occurs directly during training, the acquired skill is retained for a very short time—from a few minutes to one hour.
Important conclusion: When using inhibitors, profound memory impairments are always registered 1–2 hours after their administration, which corresponds to the time required for information to transition into long-term storage.
Specific brain proteins (according to H. Hydén)
During the learning process, as well as during concomitant glycolysis reactions in neurons, an active accumulation of specific proteins is observed in various brain structures. A number of such brain-specific proteins involved in memory processes were isolated by the researcher H. Hydén.
Key proteins involved in memory processes:
- Protein S-100. Considered by researchers to be a glial protein. During learning, it predominantly accumulates in the hippocampus. Its main function is active interaction with the outer and contractile membranes of neurons. This process proceeds only with the mandatory participation of calcium ions (Ca^{2+}).
- Protein 14-3-2. Chemically, this protein is an enzyme. Unlike S-100, its maximum accumulation occurs in the cerebral cortex.
In addition to the indicated polypeptides, the cholinoceptive protein and the enzyme acetylcholinesterase play an important role in information storage processes, ensuring the proper functioning of the synaptic apparatus.
Briefly: answers to topical questions
What are the molecular mechanisms of the cholinoceptive protein's involvement in the fixation of memory traces?
The molecular mechanism of the cholinoceptive protein's involvement consists in altering the membrane structure and improving the transmission of the nerve impulse. Under the influence of learning, the following processes occur:
- the number of cholinoreceptors in the synapses of the central nervous system increases;
- the sensitivity of neurons to the neurotransmitter (acetylcholine) increases;
- activation of cholinergic synapses causes conformational rearrangements of postsynaptic membranes.
As a result of these structural changes, synaptic conductivity increases, which ensures the formation and fixation of memory traces.
To memorize the localization of specific proteins: protein 'S' (S-100) is concentrated in the 'subcortical/old' brain—the hippocampus, while 'numbers' (14-3-2) go to the higher department—the cerebral cortex.
Class and exam questions
Do protein synthesis blockers affect short-term memory?
No, experiments show that when blockers (e.g., puromycin) are administered before training, the rate of acquiring primary skills does not change, and short-term memory remains fully intact.
How soon after the administration of inhibitors do memory impairments develop?
Profound memory impairments and loss of skills are observed 1–2 hours after the administration of blockers, which is when the transition of information into long-term memory should have occurred.
What is the function of the S-100 protein?
Protein S-100, which predominantly accumulates in the hippocampus and is considered a glial protein, actively interacts with the outer and contractile membranes of neurons with the participation of calcium ions.
What else to study on this topic
- Molecular mechanisms of protein S-100 interaction with calcium ions and membranes
- The role of glycolysis reactions in the accumulation of brain-specific proteins in neurons
- Differences in the mechanisms of action of cycloheximide and actinomycin D
- Involvement of the cholinoceptive protein and acetylcholinesterase in memory processes
Master the entire topic in the "Physiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on 'Memory proteins' and 4,128 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 114 video lessons on the subject
Other topics in the "Memory" section
Free video lessons: PhysiologyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.