Explore the complexities of receptor-mediated endocytosis and signal transduction pathways in cells. Understand how cells internalize and regulate receptors, convert extracellular signals to responses, and control gene expression. Learn about the MAPK/ERK pathway, Hedgehog signaling, and Notch signaling's role in cell communication and fate determination.
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Ligand binding induces receptor clustering and internalization via coated pits and vesicles
Recycling of Receptors
Receptors can be recycled back to the cell surface after ligand release
Degradation of Receptors
Receptors can also be targeted for degradation in lysosomes
Phosphorylation can alter receptor activity or affinity for ligands, regulating cellular response to external signals
Ligand binding to receptors on the cell surface triggers a conformational change and activation of downstream molecules
Amplification of Signals
Complex pathways allow for amplification of signals and precise cellular responses
Regulation of Signals
Multiple checkpoints in signal transduction pathways ensure precise regulation of cellular responses
Different types of receptors, such as G protein-coupled receptors and receptor tyrosine kinases, can activate or inhibit enzymes and ion channels, or directly initiate a cascade of phosphorylation events
This pathway, activated by various extracellular signals, controls cell division, differentiation, and survival through a series of phosphorylation events
This pathway demonstrates how a single molecule can induce different cellular responses depending on its concentration gradient, influencing cell fate during development
The complexity of signal transduction pathways allows for integration of multiple signals and cross-talk between different pathways to maintain cellular homeostasis
Signal transduction can lead to immediate changes, such as the opening of ion channels, or longer-term modifications, such as the induction or repression of genes
In multicellular organisms, signaling molecules coordinate processes like growth, immune responses, and tissue repair
Unicellular organisms utilize signaling for essential functions such as nutrient uptake, stress responses, and communication with other cells
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Receptor-mediated endocytosis process
Ligand binds receptor, receptor clusters in coated pits, pits invaginate forming vesicles, internalize receptor-ligand complexes.
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Fate of receptor-ligand complex post-internalization
Ligand may be released, receptor recycled to surface or degraded in lysosomes, modulating cell sensitivity.
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Receptor down-regulation mechanism
Receptors down-regulated via phosphorylation, altering activity or ligand affinity, fine-tuning response to signals.
