Signal Triggered
Signaling Mechanisms:
■ Lipid-Soluble (Steroids/Thyroid):
Directly diffuses through the hydrophobic phospholipid bilayer. Binds to a nuclear receptor, forming a complex that acts directly as a Transcription Factor modifying gene expression.
■ Water-Soluble (Peptides/Proteins):
Cannot cross the membrane. Binds to an extracellular receptor (e.g., GPCR or RTK). Triggers a Secondary Messenger Cascade (e.g., cAMP) resulting in massive signal amplification and kinase activation.
■ Lipid-Soluble (Steroids/Thyroid):
Directly diffuses through the hydrophobic phospholipid bilayer. Binds to a nuclear receptor, forming a complex that acts directly as a Transcription Factor modifying gene expression.
■ Water-Soluble (Peptides/Proteins):
Cannot cross the membrane. Binds to an extracellular receptor (e.g., GPCR or RTK). Triggers a Secondary Messenger Cascade (e.g., cAMP) resulting in massive signal amplification and kinase activation.