Signal Transduction
CHAPTER 12: Signal Transduction
What is Signal Transduction?
Signal transduction is the process by which cells respond to external signals—important for adjusting cellular activities and maintaining homeostasis.
Importance of Signal Transduction
Enables cells to receive and process information from their environment, allowing for:
Changes in composition and function of the cell,
Response to stimuli such as hormones, neurotransmitters, and other signals.
Critical for differentiation, growth, metabolism, and homeostasis.
Key Definitions
Signal: Any chemical or physical cue that can influence cellular processes.
Receptor: A membrane-bound or soluble protein or protein complex that exerts physiological effects after binding its ligand.
Signal transduction: The process by which an external signal is converted to a cellular response.
Generic Signaling Pathway Components
Signal: The input that initiates the pathway.
Receptor (sensor): Binds the signal and initiates transduction.
Transduction Cascade: A series of molecular events that amplify and propagate the signal.
Targets: Various cellular molecules (metabolic enzymes, gene regulators, cytoskeletal proteins) that implement the response:
Metabolic: Alters metabolic activity.
Enzyme: Changes enzyme activity.
Gene Regulator: Alters gene expression, changing cellular function.
Cytoskeletal Protein: Alters cell shape or motility.
Types of Receptors
Cytokine Receptors: Mediate responses to cytokines, signaling proteins that modulate immune responses.
G-Protein Coupled Receptors (GPCRs): Detect various stimuli; significant role in many physiological processes.
Integrins: Mediate cell adhesion, connecting cells to the extracellular matrix.
Frizzled: Involved in Wnt signaling.
Patched: Associated with Hedgehog signaling pathway.
Smoothened (SMO): Part of Hedgehog signaling.
Receptor Tyrosine Kinases (RTK): Mediate responses to growth factors and hormones.
Components of Signaling Pathways
Intracellular Proteins: Include cdc42, Fyn/Shc, PLC, Grb2/SOS, PI3K,
Enzymes: Such as Raf, PKC, GSK-3β, Akt, and others that facilitate the signaling cascade.
Gene Regulators: Include NF-kB, Myc, fos, jun, and others that regulate gene expression.
Apoptotic Regulators: caspases, Bcl-xL that are involved in programmed cell death.
Biological Role of Signal Transduction
Cells receive environmental signals beyond
Signal transduction is the process by which cells respond to external signals—important for adjusting cellular activities and maintaining homeostasis.
Enables cells to receive and process information from their environment, allowing for:
Changes in composition and function of the cell,
Response to stimuli such as hormones, neurotransmitters, and other signals.
Critical for differentiation, growth, metabolism, and homeostasis.
Signal: Any chemical or physical cue that can influence cellular processes.
Receptor: A membrane-bound or soluble protein or protein complex that exerts physiological effects after binding its ligand.
Signal transduction: The process by which an external signal is converted to a cellular response.
Generic Signaling Pathway Components:
Signal: The input that initiates the pathway.
Receptor (sensor): Binds the signal and initiates transduction.
Transduction Cascade: A series of molecular events that amplify and propagate the signal.
Targets: Various cellular molecules (metabolic enzymes, gene regulators, cytoskeletal proteins) that implement the response:
Metabolic: Alters metabolic activity.
Enzyme: Changes enzyme activity.
Gene Regulator: Alters gene expression, changing cellular function.
Cytoskeletal Protein: Alters cell shape or motility.
Types of Receptors:
Cytokine Receptors: Mediate responses to cytokines, signaling proteins that modulate immune responses.
G-Protein Coupled Receptors (GPCRs): Detect various stimuli; significant role in many physiological processes.
Integrins: Mediate cell adhesion, connecting cells to the extracellular matrix.
Frizzled: Involved in Wnt signaling.
Patched: Associated with Hedgehog signaling pathway.
Smoothened (SMO): Part of Hedgehog signaling.
Receptor Tyrosine Kinases (RTK): Mediate responses to growth factors and hormones.
Components of Signaling Pathways:
Intracellular Proteins: Include cdc42, Fyn/Shc, PLC, Grb2/SOS, PI3K,
Enzymes: Such as Raf, PKC, GSK-3β, Akt, and others that facilitate the signaling cascade.
Gene Regulators: Include NF-kB, Myc, fos, jun, and others that regulate gene expression.
Apoptotic Regulators: caspases, Bcl-xL that are involved in programmed cell death.