BIOL 212 Lecture Notes - Lecture 24: Protein Kinase, Autocrine Signalling, Nuclear Receptor
18 May 2018
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Lecture 24
Cell Signaling/Communication
- Processes of generating, receiving, interpreting EC signals that change the state of the cell that receives signal
- Involves signal transduction: cellular process of conversion of a message from one form to another
o Signals have to be converted cuz EC signaling molecules are diff from intracellular effector molecules
that change cellular states
EC Signaling Molecules (ligands)
- Proteins, small peptides, amino acids, nucleotides, steroids, fatty acid derivatives, dissolved gases
- From the environ
- Produced by signaling cells
o Secreted into EC space by exocytosis
o Released by diffusion thru plasma membrane
o Exposed to EC space while remaining bound to signaling cell’s surface
Receptors
- Proteins
- Frequently transmembrane proteins (cell-surface receptors)
- Can be intracellular, signal must 1st diffuse across plasma membrane
Animal Cell Signals
- Endocrine: long range signaling by hormones
o Sent to entire body
o Ligands are hormones
o Hormone producing cell is endocrine cell
- Paracrine: short range
o Released into EC space
o Acts locally on neighboring cells
o Inflammation, wound healing, development
o When signal affects signal-sending cell itself, autocrine signaling
- Synaptic: highly localized release ligand which can occur far away from cell body of neuron
o Fast
o Ligands are neurotransmitters released at synapses
o Inter-conversion b/t electrical/chemical signals take place
- Contact-Dependent: does not involve release of EC signaling molecules
o Embryonic development, tissue remodeling/maintenance, immune system
- Notch-Delta Signaling
o Establishes diff b/t adjacent cells
o Notch is receptor protein, Delta is membrane-bound inhibitory signal protein
Cellular Response
- Depends on current state of cell (ex. Contraction, slower HR, secretion)
- Fast or slow
Signal Pathways
- Common pathways:
o EC signal molecule→ receptor protein → intracellular signaling molecules → effector proteins → target
cell responses
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