Cell signalling Flashcards
What is autocrine signalling
Cell signals itself
What is endocrine signalling?
Signal to a far away cell
What is paracrine signalling?
Cell signals to a close by cell
What is intercellular signalling?
How one cell communicates with other cells within the organism
- direct physical contact
What is intracellular signalling?
How signals from a receptor are transmitted within the cell
- causes cellular behavioral changes
How do extracellular signal molecules ligate to cells?
Ligands (ESM) can bind (ligate) to cell-surface receptors or intracellular receptor
True or false: most signal molecules are hydrophobic?
Most are hydrophilic and unable to cross plasma membrane
What is the difference between cell-surface receptors and intracellular receptors?
Cell-surface receptor are hydrophilic therefore are on the surface
Intracellular receptors are hydrophobic therefore are in the cell
What are the four forms of intracellular signalling?
Contact-dependent
Paracrine
Synaptic
Endocrine
What form of intercellular signalling are nerve cells?
Synaptic
What form of intercellular signalling are hormones?
Endocrine
What form of intercellular signalling are budding yeast cells?
Paracrine
What form of intercellular signalling are immune cells?
Contact-dependent
What is the difference between synaptic and endocrine signalling?
Endocrine: transport through blood stream
Synaptic: transport through axons
What are the effects of cell signalling?
Survive, grow+divide, differentiate, die
What are the receptor classes?
Nuclear, ion channels, G-protein coupled, enzyme coupled
Explain nuclear receptors
Binding of ligand to receptor causes a conformational change
Give an example of nuclear receptors
Steroid hormones signalling
Explain ion-channel linked receptors
Convert chemical signals to electrical signals
- gap junctions
Explain G-protein link receptor
Signal transduction involves the production of 2nd messengers
- chemokine receptors
Explain enzyme-linked receptor
Protein kinase receptors
- insulin receptors
Explain ion channel coupled receptors
Reside within excitable tissue
- neuromuscular junction
How is signalling information encoding affected by phosphate?
Through the addition/removal of phosphate group
- Phosphate added to protein
- GDP gets substituted by GTP
What is the effect of phosphorylation?
Change of charge results in a conformational change (shape is different)
Where is the G-protein in G-protein-coupled cell-surface receptors found?
The receptor sits in the cell membrane but the G-protein is inside the cell close to the membrane
Explain G-protein-bound cell-surface receptor signalling
GDP is bound, receptor inactive
Through a signal, GDP is replaced with GTP
G proteins
What is cyclic AMP and why is it important?
Synthesized by adenylyl cyclase from ATP
Importance intra-cellular signalling (2nd messenger)
What is an example of an important signalling complex
CD4 and T-cell receptor
Changes in cell adhesion, gene expression and T cell regulation
What is scaffold protein?
Where signalling molecules are kept together
They get activated together
What is mitogen-activated protein kinase (MAPK) pathway?
Activated by growth factors
Cascade of kinases: Raf-Mek-Erk
Leads to change in protein activity and changes in gene expression
