W1/L3 - Cell Communication and Receptor Families Flashcards
Textbook concepts
Campbell Biology, 11th edn, 2017 – Chpt 11
Concept 11.1: External signals are converted to responses within the cell
Concept 11.2: Reception: A signalling molecule binds to a receptor protein, causing it to change shape
Concept 11.3: Transduction: Cascades of molecular interactions relay signals from receptors to target molecules in the cell
Concept 11.4: Response: Cell signalling leads to regulation of transcription or cytoplasmic activities
Cell to cell communication: Local vs. long‐distance signaling
Local signaling:
Auto prime signaling, signals in itself
Paracrine signaling. A signal cell acts on nearby target cells by secreting molecules of a local regulator (Growth factor)
Synaptic signaling. A nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell, such as a muscle or another nerve.
Long-distance signaling
Endocrine signaling. Specialized endocrine cells secrete hormones into body fluids, often blood. Hormones reach most body cells but are bound by an affect only some cells
Cell to cell communication: 3 stages of cell signalling
signalling molecule finds receptor, binds to it (reception event) which is then transducted.
Three relay molecules in a signal transduction pathway, changes happen inside the cell (Transduction)
Activation of cellular response, such as activation of glycogen phosphorylase
Receptor families
Thre of which, the signaling molecule does not enter the cell. One of them does, usually bound to a carrier protein as they are hydrophobic.
Campbell Biology, 11th edn, 2017 – Chpt 11
Concept 11.1: External signals are converted to responses within the cell
Concept 11.2: Reception: A signalling molecule binds to a receptor protein, causing it to change shape
Concept 11.3: Transduction: Cascades of molecular interactions relay signals from receptors to target molecules in the cell
Concept 11.4: Response: Cell signalling leads to regulation of transcription or cytoplasmic activities
Receptor families
Plasma Membrane Receptors
Ion channel receptors: - Na+ channel opened by ligand – e.g. nicotinic receptors for acetylcholine – fast neurotransmission
G protein-coupled receptors: 7 TM-spanning regions - all aspects of physiology and pharmacology
Receptor tyrosine kinases: e.g. insulin receptors - metabolism, cell growth, cell reproduction
Intracellular receptors
Steroid receptors
Ion channel receptors
Ligand-gated ion channel
Example: nicotinic acetylcholine receptors.
Embedded in the cell membrane, 5 peptides
G protein‐coupled receptors (GPCRs)
Most complicated family, spend most time studying this!
- Seven transmembrane spanning domains (7 TMDs)
- The largest family of receptors:
>1000 members in the human genome. 150 orphans. >50% of current drugs target GPCRs
• Activated by a variety of stimuli:
light, ions (eg. Ca2+), odourants, gustative molecules, neurotransmitters, hormones, peptides, proteins.
• GPCRs interact with heterotrimeric G proteins to control the activity of enzymes, ion channels, and intracellular signal transduction pathways
Receptor tyrosine kinases: e.g. insulin receptors - metabolism, cell growth, cell reproduction
How does insulin work?
Phosphorylation cascades
- Mediated by enzymes called KINASES - these transfer phosphate and activate or inactivate target proteins (Phosphate = PO4-
Receptor tyrosine kinases. Need 2 molecules to activate
phosphorylated proteins can cause changes in formation, interactions or change in cellular location. These changes lead to activation or inactivation of the target proteins!
Intracellular receptors - Steroid receptors
Completely intercellular. Hormone goes inside of cell to activate the receptor.
Receptor complex bounded to hormone goes into nucleus and binds to DNA which creates mRNA to create a new protein which is then the final response.
This process takes a lot longer than all other families
