Block 1 Lecture 10

Question 1

what are the 4 different types of cell-to cell communication

Answer 1

1. contact- dependent
2. paracrine
3. ) endocrine
4. synaptic

Question 2

what relays the signal after receptor activation?

Answer 2

second messengers and intracellular transducers

Question 3

what can cell response be caused by

Answer 3

1. speeding or slowing of a biochemical reaction
2. causing increase of decrease in the abundance of a particular protein by altering central dogma
3. changing activity of a protein by adding or removing a phosphate group
4. changing the location of a protein
5. starting or stopping release of a secreted product

Question 4

what are the 3 types of plasma membrane receptors

Answer 4

1. ion channel linked receptors
2. G-protein linked
3. enzyme linked

Question 5

what do G protein linked receptors do

Answer 5

activate a class of GTP binding proteins

Question 6

how are G proteins turned off

Answer 6

by hydrolyzing GTP to GDP

Question 7

what happens in GPCR activation

Answer 7

• ligand binding causes GTP to exchange for GDP
• alpha subunit dissociates from the complex and activate signaling pathways that bring cell response
• different g-alpha subunits which activate different signaling pathways are associated with different receptors

Question 8

what do G proteins do

Answer 8

• some regulate ion channels
• others activate adenylate cyclase increasing cAMP
• some activate phospholipase C increasing IP3 and DAG

Question 9

what is the cyclic amp pathway

Answer 9

• GPCRs can increase cAMP by activating Gs, a stimulatory protein that activates adenyl cyclase
• cAMP activates protein kinase A and this can bring about many different types of cell responses by causes protein phosphorylation
• protein kinase A can interact with cAMP response element CREB to activate transcription

Question 10

what is the IP3 pathway

Answer 10

• GPCR signaling can involve fatty acids
• IP3 is released into cytosol and stimulates Ca2+ release from ER
• elevated Ca2+ in cytosol activates calcium dependent protein kinases, protein phosphates that in turn alter the activities of target proteins

Question 11

what is the DAG pathway

Answer 11

• GPCR singling can involve fatty acids
• DAG is produced in addition to IP3
• DAG remains in membrane of protein kinase C family

Question 12

what are the 2 positions of cell receptors

Answer 12

surface cell receptors and intracellular receptors

Question 13

what are the 5 different mechanisms to prevent overstimulation

Answer 13

1. receptor sequestration
2. receptor down regulation
3. receptor inactivation
4. inactivation of signaling protein
5. production of inhibitory protein