SIGNAL TRANSDUCTION MECHANISMS Flashcards
What does the signal represent?
information detected by specific receptors & converted to a cellular response, which involves a chemical process.
Signal transduction
The conversion of information into a chemical change.
Stages of signaling
- Reception
- Transduction
- Response
- Resonpse
Ion transport. Protein modification
(phosphorylation of target proteins, which changes their activities). Gene expression
Signals
*Antigens * Light * Developmental signals * Mechanical contact * Growth factors * Neurotransmitters * Hormones * Food
Signals 2
- ECM components * Odorants * Gustatory (Taste) * Pheromones * Cell surface glycoproteins / oligosaccharides
Features of signal transduction systems
- Specificity * Sensitivity * Amplification * Desensitization-adaptation * Integration
Specificity
signal molecule fits binding site on its complementary receptor; other signals don’t fit
amplification
when enzymes activate enzymes, the number of affected molecules increases geometrically in an enzyme cascade
desensitization / adaptation
receptor activation triggers a feedback circuit that shuts off the receptor/removes it from the cell surface
When a signal is present continuously, the receptor system is turned off
desensitization
When the stimulus falls below a certain threshold, the system again becomes sensitive
adaptation
Integration
when 2 signals have opposite effects on a metabolic characteristic like the concentration of a 2nd messenger X, or there membrane potential Vm, the regulatory outcome results from the integrated input from both receptors
ability of the system to receive multiple signals and produce a response appropriate to the needs of the cell or organism.
Integration
Importance of Lipid Rafts
Rafts sequester groups of signaling proteins & receptors in small regions of the plasma membrane, enhancing their interactions & making signaling more efficient.
