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BIOC192 > Lecture 13: ACTIVATION AND INHIBITION OF PROTEINS (PART 1) > Flashcards

Lecture 13: ACTIVATION AND INHIBITION OF PROTEINS (PART 1) Flashcards

1
Q

What is the first common step in activation and inhibition of proteins?

A

Chemical substance travels from its source

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2
Q

What happens after the chemical substance travels from its source?

A

Chemical substance interacts with the target protein- binding/reception

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3
Q

What is reception?

A

When the protein receives the substance

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4
Q

What happens after the chemical substance interacts with the target protein- binding/reception?

A

The binding event effects the protein to either activate or inhibit it

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5
Q

What happens after the binding event effects the protein to either activate or inhibit it?

A

Functional consequences that change the cellular response

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6
Q

How does the activation and inhibition relate to HIV protease?

A

Saquinavir binds to HIV and inhibits any further action

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7
Q

What are receptors?

A

A cellular protein (or assembly of proteins) that control chemical signalling between and within cells

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8
Q

How many individual receptor proteins are there?

A

About 1000

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9
Q

What do receptors control?

A

Many important physiological processes, including sight, smell and taste

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10
Q

What are receptors the cellular targets for?

A

Many drugs and some toxins

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11
Q

What do one third of drugs do?

A

Activate or inhibit receptors

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12
Q

How do enzymes and receptors compare in binding sites?

A

Enzymes typically have one active site and receptors can have several binding sites

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13
Q

How do enzymes and receptors compare in what they bind?

A

Enzymes bind substrates and receptors ind ligands

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14
Q

How do enzymes and receptors compare in what they do to what binds?

A

Enzymes change substrate to product and receptors release the ligand unchanged

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15
Q

How do enzymes and receptors compare in where they are found?

A

They can both be found membrane bound or free in the cytosol

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16
Q

What can be don’t with both enzymes and receptors?

A

They can be activated, inhibited or used as drug targets

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17
Q

What are the main classes of receptors?

A

Ligand-gated ion channels, G protein coupled receptor (GPCR) and receptor tyrosine kinase (RTK)

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18
Q

What is different between the three receptor classes?

A

Their structure which is important to their function

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19
Q

What is the same between the three receptor classes?

A

They have the same overall steps of activation and inhibition but the exact details differ

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20
Q

What is a ligand?

A

The general term given ti a chemical substance that specifically binds to a receptor

21
Q

What may ligands be?

A

Diverse in chemical structure, ranging from small molecules to large peptides and even proteins

22
Q

What are the types of ligands?

A

Endogenous and exogenous

23
Q

What are endogenous ligands?

A

Ligands produced in the body

24
Q

What are examples of exogenous ligands?

A

Drugs and toxins

25
Q

What do all ligands do?

A

Make chemical contacts with their specific receptors

26
Q

Where are most receptors found?

A

On the outer cell membrane, where they act as sensors of the extracellular environment

27
Q

What does the ligand not usually have to do?

A

Pass through the membrane

28
Q

What is the receptor known as?

A

The gate keeper of cellular activity, controlling it from the cell surface

29
Q

How can intracellular responses to extracellular signals be produced?

A

By a membrane receptor being activated (ligand binding)

30
Q

What is there between ligands and receptors?

A

Specificity

31
Q

When will activation and inhibition happen?

A

only when the ligand receptor pairing is correct

32
Q

What does the size and shape of the ligand match?

A

The corresponding receptor ‘binding pocket’ allowing enough chemical interactions for binding to occur

33
Q

What happens if the ligand doesn’t match?

A

There will be no binding to the receptor

34
Q

What is the mechanism for binding to receptor proteins used for?

A

To make drugs that bind only to certain receptor targets

35
Q

What do medicinal chemists often do?

A

Often start with the chemical structure of an endogenous ligand, making new molecules from this to produce safe and effective medicines

36
Q

What is an example of a medicine made by modifying the structure of an endogenous ligand?

A

Adrenaline (small molecule, endogenous ligand) is modified to form salbutamol (ventolin) which is an asthma drug

37
Q

What can salbutamol do?

A

Activate the same receptor as adrenaline and mimic its effects to cause bronchodilator because both ligands can make similar chemical contacts with the receptor

38
Q

What is an agonist?

A

A chemical substance (ligand) that binds to a receptor and activates it (may be endogenous or exogenous)

39
Q

What happens first in activation of a receptor?

A

The agonist binds

40
Q

What happens after the agonist binds?

A

The receptor undergoes a conformational (Shape) change to become activated - different ligands can cause different shape changes

41
Q

What happens after the receptor is activated?

A

Active receptor starts a chain of events where messages are passed on through the cell via a process called signal transduction until there is a cellular response

42
Q

What do different receptors use?

A

Different types of relay molecules to pass on the message

43
Q

What is an antagonist?

A

A chemical substance (ligand) that binds to a receptor and prevents activation by an agonist (mainly exogenous)

44
Q

What happens first in receptor inhibition?

A

Antagonist binds and blocks agonist binding

45
Q

What happens after the antagonist binds and blocks agonist binding?

A

Receptor remains inactive

46
Q

What happens after the receptor is inactivated?

A

Signal transduction does not occur so there is no cellular response

47
Q

What does adrenaline do?

A

Acts as an agonist to activate the beta-adrenergic receptor (a GPCR). Signal transduction&raquo_space;> Bronchodilation (cellular response)

48
Q

What does insulin do?

A

Acts as an agonist to activate the insulin receptor (a RTK). Signal transduction&raquo_space;> Glucose uptake (cellular response)

BIOC192 (38 decks)

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