Signal Transduction Mechanisms Flashcards
What is VEGF?
Vascular endothelial growth factor
What is paracrine signalling?
Target cell is close to signal releasing cell, and signal chemical is broken down too quickly to be carried to other parts of the body. E.g. Clotting factors in thrombus formation.
What is synaptic signalling?
From a nerve to a target cell. E.g. Acetylcholine to muscle cell.
What is autocrine signalling?
Cell secretes a chemical messenger that signals the same cell. E.g. Cancer cells.
What is endocrine signalling?
Long distance signalling involving hormones. E.g. Insulin is released from pancreas after eating.
What is nervous shouted signalling?
Long distance signalling, involving neurones.
What is an advantage of a signal transduction mechanism?
Low amounts of hormones/neurotransmitter can have large effects on the body, as the signal is amplified.
How do G Protein Controlled Receptors activate G Proteins?
Inactive G proteins contain a GDP bound to their alpha subunit. G proteins become activated as the GPCR swaps the GDP for a GTP, then allowing the G protein to activate its effector and transmit the signal.
What do G proteins activate in the cell?
They activate enzymes which generate secondary messengers - e.g. Adenyl Cyclase, which goes on to form cAMP
How do receptor tyrosine kinases work?
A signal molecule in the form of a dimer activates the receptor. Tyrosine kinase is stimulated, and it thus becomes phosphorylated. This means intracellular signalling proteins bound to the tyrosine kinase will become activated too, and signal is relayed to proteins of the cell’s interior.
How are G protein controlled receptors different to receptor tyrosine kinases?
GPCR - rapid responses (e.g. With adrenaline), has 7 transmembrane domain, diverse ligands.
RTKs - only a single transmembrane domain, activated only by dimers, direct regulation of effectors, slower responses.
Which type of hormones use nuclear receptors?
Steroid hormones.
How do nuclear receptors work?
The receptors are transcription factors, that directly regulate gene expression. Conformational change activates the receptor protein, activated receptor will bind to regulatory region of target gene and activate transcription.
How does Nitric Oxide work in smooth muscle?
It targets guanylyl cyclase, generating cGMP which causes vasodilation.
