Receptors and their signal transduction Flashcards
What are the functions of receptors?
- they need to recognize the mediator
- recognize ligands (molecules that bind to receptors)
- the target cell must revoke a biological response
What is contact dependent intercellular communication?
the cell communication is dependent on contact
→ the cells must make contact in order for cell communication to occurr
What is a paracrine mediator?
molecules that are released from one type of cell and act locally on a different type of target cell
What is synaptic intercellular communication?
neurons trasnsmit electrical signals along their axons and release neurotrasmitters at synapses that affect the function of other neurons or cells that are distant from the neuron cell body
What is endocrine intercellular communication?
hormones that are secreted into the blood and spread in the body
example: hormone
What is autocrine secretion?
release of a molecule that affects the same cell or other cells of the same type
What are the types of intercellular communication?
- gap junctions
- autocrine mediator
- paracrine
- contact dependent communication
- synaptic -endocrine
What are the conditions of a receptor in regards to the ligand bonding?
- the binding of ligand to the receptor has to be reversible
- can be saturated
- the receptor has to be specific, however the specificity is not absolute
What are the two types of intracellular signaling proteins that act as molecular switches?
- signaling by phosphorylation
- signaling by GTP- binding protein
Describe the mechanism of signaling by phosphorylation.
- activated by the addition of a phosphate group
- inactivated by the removal of the phosphate
- The phosphate is added covalently to the signaling protein by a protein kinase
Describe the mechanism of signaling by GTP-binding-proteins.
- activated by the addition of a phosphate group
- inactivated by the removal of the phosphate
- A signaling protein is induced to exchange its bound GDP for GTP
What are the two types of signaling molecules?
- plasma membrane receptors
- intracellular receptors
How do signaling molecules work?
- they directly bind to their cognate receptors located in the plasma membrane
- when ligand is bound they regulate gene transcription
What is another possible means for the path of a signal molecules?
- bind to carrier proteins in blood and diffuse across the plasma membrane
- they bind to cognate so-called nuclear receptors in the cytosol or nucleus
- when ligand is bound, they regulate gene transcription
What is the general mechanism of how cells communicate?
- A ligand binds to a receptor which may be located in the plasma membrane, cytosol, or nucleus.
- This binding activates intracellular signaling proteins
- These proteins interact with and regulate the activity of one or more target proteins to change cellular function.
What do signaling moleculares regulate?
- cell growth
- cell division
- differentiate and influence cellular metabolism
- cytoskeletal-associated events (cell shape, division, migration, and cell to cell matrix adhesion)
How do signal molecules modulate the intercellular ion composition?
they regulate the activity of ion channels and transport proteins
What are examples of plasma membrane receptors?
- G protein-coupled receptors
- Ion channel receptors
- Receptors with enzyme activity
- Enzyme activity-linked receptors