Receptors Flashcards
How is the secondary messenger activated in GPCRs?
Dissociation of a and B subunits, activated by exchange of GDP for GTP
Give three effects of GPCRs?
- Increase or decrease in cAMP
- Increase in Ca2+
- Increase in IP3 (lipid mediators)
What is the parathoid hormone receptor?
Expressed in the kidneys, regulates calcium and phosphorus concentration. Mutation causes constitutive activation and so constant cAMP activation leading to short-limbed dwarfism
What is Grave’s disease?
Causes hyperthyroidism via TSHR agonistic autoantibodies, excess generation of cAMP
What does an agonistic antibody do?
Binds a receptor and prevents binding of its natural ligand
What does cholera toxin do?
Uses ganglioside Gm1 as an entry receptor into cells, catalyses ADP-ribose transfer from NADH to an arginine residue to Gas. Prevents hydrolysis of GTP so cAMP is constitutively upregulated to release Cl- into the gut.
What does pertussis toxin do?
Whooping cough, affects ion flux into lung epithelial
What can non-germline defects do?
Give mosaic/sporadic phenotypes
How do enzyme coupled tyrosine kinases signal?
Via phosphorylation cascades
What can cause diabetes type II?
- Endocytosis and degradation of the receptor
- Phosphorylation of the receptor (switched off)
- Down-regulation of P13K and IRS by high glucose levels and free fatty acids
What do adhesion receptors allow?
Spatial pattering, migration, differentiation, guidance, mmorphogenesis etc.
Name 5 adhesion receptors
- Ig superfamily
- Cadherins
- Integrins
- Selectins
- Proteoglycans
What is the leukocyte adhesion-cascade?
Cells need to move from the blood into the tissues in case of an infection. Recruitment of cells uses lots of different types of adhesion molecules to stick, roll and transmigrate.
What is involved in capture and rolling?
Selectins, bind sialyl-Lewis x sugars for capture, and phosphoinositide-3-kinase results in slow rolling.
What is outside-in signalling?
Binding of receptor causes a phenotypic change
