Receptors Flashcards
What types of receptors are there in terms of cell specificity?
Cell type specific and cell specific.
Give the cell specific types of receptors?
Contact-dependent and synaptic.
What are the three types of receptors?
Enzyme-coupled, ion channel coupled and G-protein coupled receptors.
Which is the largest family of receptors with over 700 cell surface receptors?
G-protein coupled receptors
What depends on G-protein coupled receptors?
Sight, smell and taste senses, many signal from the external environment but also other cells.
What act on G-protein coupled receptors?
Proteins, small peptides, derivatives of amino acids and fatty acids, photons of light and all the molecules we smell/taste.
What structure do G-proteins coupled receptors have?
A single polypeptide chain that threads across the membrane several times- highly conserved.
What do G-protein coupled receptors use to relay the signal in the cells interior?
A G-protein as a secondary messenger.
What disease is caused by a mutation in the parathyroid hormone receptor in the kidney?
Jansen’s metaphyseal chondrodysplasia (short limbed dwarfism)
What does the mutation in the parathyroid hormone cause?
Constitutive activation of the receptor which leads to poor regulation of calcium and phosphorous concentration and chondrocyte growth.
What diseases are associated with the thyroid stimulating hormone receptor?
Grave’s disease and Hashimoto’s
What is cell communication vital for?
Spatial patterning, allows distal communication, cell proliferation, apoptosis, differentiation, cell guidance and maturation.
Describe Grave’s disease?
Causes hyperthyroidism due to agonistic autoantibodies which effect the thyroid stimulating hormone receptor chasing excess cAMP production.
Symptoms include weight loss, goitre, opthalmopathy etc.
Describe Hasimoto’s disease?
Caused by antagonistic antibodies resulting in less cAMP production.
Symptoms include weight gain, often post partum.
How does cholera toxin use hosts receptors?
Uses ganglioside Gm1 to enter and it’s result effects cAMP production
How does pertussi toxin use the host receptors?
Prevents activation of Gai via ADP-ribosylation leading to increase in cAMP effecting ion influx into the lung epithelial cells.
What is McCune-Albright Syndrome?
Activating Gsa mutations cause over activation. Two main mutations: Arg201 in the GTP/GDP binding domain of the protein which is the cholera toxin binding site and Gln227 required for intrinsic GTPase activity.
What is the café-au-lait phenotype?
A non-germline (somatic) defects phenotype. Increased in melanocytic-stimulating hormone-Gs-cAMP pathways causes stimulation of melanin pigment production.
What is the fibrous dysphasia osteoblasts dysfunction?
Bone dysfunction
What is pseudohypoparathyroidism?
Caused by a loss in GNAS function, essential for parathyroid signalling. Has different phenotype a dependent on whether it is inherited maternally or paternally.
What are the six classes enzyme-couple receptors?
Receptor tyrosine kinases, tyrosine kinase associated receptors, receptor threonine/serine kinases, histidine kinase associated receptors, receptor quanylyl cyclase receptors, receptor like tyrosine phosphatases.
What is the structure of enzyme-coupled receptors?
Transmembrane proteins that have a ligand-binding domain on the outer surface of the plasma membrane. They have a cytosolic domain which has intrinsic enzyme activity or associated directly with the enzyme.
How do enzyme-coupled signal?
Via a phosphorylation cascade, have many growth factors: VEGF, EGF, M-CSF, ephrin and insulin receptors.
How does a receptor tyrosine kinase act after ligand binding?
Cross phosphorylation their cytoplasmic domain on multiple tyrosine. Trans-autophosphorylation stimulates the kinase and produces a set of phosphotyrosine that serve as docking sites for a set of intracellular signalling proteins which bind via their SH2 or PTB domains. Ras-GEF is activated which activates the monomeric GTPase Ras, which activates a 3 part MAP kinase pathway.
What is insulin receptors main role?
To increase glucose uptake
What does the insulin receptor do in diabetes?
Becomes desensitisation: endocytosis and degradation receptor due to phosphotyrosine phosphatases (PTPases), down modulation of P13K and IRS proteins (both downstream signalling components)by high glucose and free fatty acids.
What receptors do all multicellular organisms require?
Adhesion receptors
What adhesion receptors allow?
Spatial patterning, migration, differentiation, guidance, morphogenesis, cell-to-cell and cell-to-matrix interactions. Some mediate homotypic interactions and some heterotypic.
What are the types of adhesion receptors?
Ig superfamily, Cadherin, intergrins, selectins, proteoglycans.
Describe the leukocyte adhesion cascade?
- Capture: mediated by selectins
- Rolling: mediated by selectins
- Self rolling: mediated by selectins, activated by chemokines
- Arrest: mediated by integrins
- Adhesion, strengthening and spreading
- Intravascular crawling
- Paracellular transmigration
- Transcellular transmigration
What is a disease caused by migration defects in neutrophils?
Leukocyte adhesion deficiency (LAD), causes recurrent infections.
In LAD1, 2 and 3 what is deficient?
LAD1: CD18 (a crucial integrin)
LAD2: fucosyl transferase (important for generating selectin ligands)
LAD3: activation of integrins
What embryonic processes involve cell-adhesion?
Segregation of tissues during neural tube formation, dispersion of cells from a solid tissue, migration of cells allow adhesive guidance cues, cavity formation and cell-to-call communication through gap junctions.
What is metastasis?
The spread/movement of cancer cells from one organ or tissue to another via the blood stream or lymph system.
What are microbial receptors?
Receptors of the immune system which need to be able to recognise self and non-self.
What type of microbial receptors have evolved and what do they do?
Surface pattern recognition receptors, which recognise various pathogen associated molecular patterns (PAMPs). They are able to signal to produce appropriate responses and produce various cytokines and immune regulators.
What are the major types of surface pattern recognition receptors?
Toll receptors and carbohydrate binding lectins.
What defects in surface pattern recognition receptors are there?
Toll mutant drosophila or candida infection.
How do listeria pathogens exploit host receptors?
CD4 on T cells normally interacts with MHC2 on APCs leading to activation of T helper cells, allowing the hydrophobic fusion protein to be inserted into the membrane but listeria exploits phagocytic receptors to enter the cell.
