BIO 011 Lecture Notes - Lecture 30: Signal Transduction, Autocrine Signalling, Adenylyl Cyclase
Chap 7 – Cell Signaling
Jadzia Wray
How does cell signaling work?
- To respond to a signal, a cell must have a specific receptor that can detect it.
- A signal transduction pathway is the sequence of events that lead to a ell’s respose to a sigal.
Signal Transduction
Signals can act near and far
- Autocrine signals affect the cells that made them.
- Juxtacrine signals affect only adjacent cells.
- Paracrine signals affect nearby cells.
- Endocrine signals travel to distant cells, usually via the circulatory system.
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What happened after signals are received?
Crosstalk – signal transduction pathways are often
interrelated
- Pathways can branch; one activated protein may
activate multiple pathways.
- Multiple pathways can converge on a single
transcription factor.
- One pathway may be activated while another is
inhibited.
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Receptors and Ligands
- KD is the dissociation constant, a measure of the affinity
of the receptor for its ligand.
- The lower the KD, the higher the binding ability of the
ligand and receptor.
- Very low KD values allow receptors to bind their ligands
at very low ligand concentrations.
Where are receptors located?
Intracellular receptors: Small or nonpolar ligands can diffuse across
the cell membrane (e.g., estrogen).
Membrane receptors: Large or polar ligands bind to cell membrane
receptors (e.g., insulin).
In eukaryotes:
- Ion channels
- Protein kinase receptors
- G protein-linked receptors
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Document Summary
To respond to a signal, a cell must have a specific receptor that can detect it. A signal transduction pathway is the sequence of events that lead to a (cid:272)ell"s respo(cid:374)se to a sig(cid:374)al. Autocrine signals affect the cells that made them. Endocrine signals travel to distant cells, usually via the circulatory system. Crosstalk signal transduction pathways are often interrelated. Pathways can branch; one activated protein may activate multiple pathways. Multiple pathways can converge on a single transcription factor. One pathway may be activated while another is inhibited. Kd is the dissociation constant, a measure of the affinity of the receptor for its ligand. ligand and receptor. at very low ligand concentrations. The lower the kd, the higher the binding ability of the. Very low kd values allow receptors to bind their ligands. Intracellular receptors: small or nonpolar ligands can diffuse across the cell membrane (e. g. , estrogen). Membrane receptors: large or polar ligands bind to cell membrane receptors (e. g. , insulin).
