Topic 6 - Controlling Cell Behaviour Flashcards
What is the central paradigm for cellular communication?
Signal - receptor - transduction process - cellular response.
Recall from your previous studies some of the types of extrinsic signals that cells can detect and respond to.
Cells respond to a wide range of extrinsic signals that include chemical messengers (e.g. hormones, growth factors, neurotransmitters), electrical impulses, mechanical forces, pH, heat and light.
Explain mitogen-activated protein kinase (MAP kinase or MAPK)
Kinases that were so-named because they were first identified in the signalling pathways activated by molecules that stimulate cells to divide (i.e. mitogens). MAP kinases are components of intracellular signalling cascades that are activated by extrinsic ligands binding to cell membrane receptors; often function in a cascade of kinases in which the final kinase phosphorylates target proteins including transcription factors.
What are molecular switches?
Cellular proteins that change between an active (on) and an inactive (off) conformation. The conformational change is usually brought about by the addition/removal of a phosphate group, either by phosphorylation/dephosphorylation of an amino acid residue or by GTP/GDP exchange.
Explain covalent modification?
The covalent linking to protein amino acid side-chains of groups that can affect their function and/or the localisation of the protein in the cell; such modifications include methylation, acetylation, glycosylation, phosphorylation and lipidation.
Explain allosteric regulation
In many proteins, the binding of a particular ligand at one site affects the conformation of a second remote binding site, for another ligand, on the same protein. This is an important mechanism by which a protein’s binding capacity and/or its activity is regulated.
Explain phosphorylation
The transfer of a phosphate group from one molecule to another. Many proteins are phosphorylated by kinases that transfer the terminal phosphate group from ATP. Phosphorylation changes the conformation of a target protein so that its activity, or ability to interact with other molecules, is altered.
What response do trimeric and monomeric G-proteins play a role in?
The mating response.
Explain how yeast cells find a mate
By organising the signalling complexes near to the activated GPCRs, the yeast cells can extend a shmoo in the correct direction to find a cell to mate with.
