Protein activation/inhibition, receptors, signal transduction Flashcards

1
Q

What are the 4 common steps to producing a cellular response?

A
  1. chemical substance travels from source
  2. binds to target protein
  3. causes activation or inhibition
  4. change to cellular response
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2
Q

Name differences between enzymes and receptors (3)

A

• enzymes have 1 active site while receptors can have multiple binding sites
• enzymes bind ‘substrates’, while receptors bind ‘ligands’
• enzymes change substrate into product, while receptors release ligand unchanged

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3
Q

What is the same about enzymes and receptors?

A

• can be either membrane bound or free in the cytosol
• can be activated or inhibited

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4
Q

What property ensures that the right ligand binds to open the receptor?

A

specificity

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5
Q

What is an agonist?

A

A chemical substance which binds to a receptor and ACTIVATES it.

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6
Q

What happens to the receptor when the ligand binds

A

undergoes a conformational change in order to be become activated

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7
Q

What is an antagonist?

A

A chemical substance which binds to a receptor and PREVENTS ACTIVATION by an agonist.

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8
Q

Does the receptor undergo a conformational change when an antagonist binds?

A

No, because it is not activated

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9
Q

What is a second messenger?

A

Relay molecules used in signal transduction to transmit signal from receptor to other relay molecules, free to move in cell (i.e. not membrane bound)

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10
Q

What do GPCR use to start signal transduction?

A

G proteins, which then communicate to other proteins in the cell

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11
Q

What do RTKs use to start signal transduction?

A

phosphorylation of adaptor proteins

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12
Q

What is a widespread mechanism for regulating protein activity?

A

Phosphorylation and dephosphorylation

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13
Q

What is phosphorylation?

A

when protein kinases transfer phosphates from ATP to protein

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14
Q

What are the 3 types of receptor that we study?

A

GPCRs, RTKs, ligand-gated ion channels

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15
Q

How do ligand-gated ion channels work?

A

an agonist bind which causes an conformational change to activate/open the receptor and allow ions to flow

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16
Q

Which of the 3 types of receptors carry out ‘fast signalling’?

A

ligand-gated ion channels

17
Q

What is ‘cross-talk’?

A

when relay molecules from 2 different receptors are needed to produce a response.

18
Q

How can the same receptor/ligand pairing result in different effects in different cells?

A

Because they use and have present different relay molecules for signal transduction

19
Q

What type of receptor is the insulin receptor?

A

RTK

20
Q

What happens in muscle/adipose cells when the insulin receptor is activated?

A

Receptor activation causes phosphorylation of adaptor protein and further signal transduction events, leading to GLUT-4 translocation (exocytosis of protein to cell surface, for glucose entry)

21
Q

What happens in liver cells when the insulin receptor is activated?

A

Receptor activation causes phosphorylation of adaptor protein and further signal transduction events, leading this time to glycogen synthesis

22
Q

Compare and contrast between the effects of insulin binding fo liver vs muscle cells

A

Different cells, same ligand, same receptor, different pathway, different effects (but complementary)

23
Q

What type of receptor is the glucagon receptor?

A

GPCR

24
Q

What happens when the glucagon receptor is activated?

A

Receptor activation causes G protein activation and further signal transduction events, leading to glycogen breakdown

25
Q

What type of receptor is the GLP-1 receptor?

A

GPCR

26
Q

Where is GLP-1 produced and what cells does it act on?

A

Produced in the gut, acts on pancreatic b cells

27
Q

What happens when the GLP-1 receptor is activated?

A

Receptor activation causes G protein activation and further signal transduction events, leading to INSULIN SECRETION