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Endo/Repro > 01a: Hormone-Receptor Interactions > Flashcards

01a: Hormone-Receptor Interactions Flashcards

1
Q

T/F: All hormones, to initiate a response, must bind to receptors on target cells.

A

False - receptors can be inside target cell

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2
Q

T/F: Hormone-Receptor Interaction has both high specificity and high affinity.

A

True

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3
Q

T/F: Hormone-Receptor interaction, in many cases, is a simple, unimolecular, reversible reaction.

A

False - simple, bimolecular, reversible

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4
Q

In order for H-R complexes to form in presence of low hormone levels, (KA/KD) constant must be very high, which means (KA/KD) is very (high/low).

A

KA;
KD (reciprocal of KA)
Low

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5
Q

T/F: Frequently, the H-R interaction is defined by its KA.

A

False - by its KD

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6
Q

If the free hormone concentration is equal to KD, what does that tell you about the receptors?

A

Half are occupied/bound

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7
Q

In order to have about 90% occupancy of hormone receptors, (X) should be increased (Y)-fold over (Z).

A 
X = free hormone concentration
Y = 10
Z = KD
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8
Q

If there’s about 10% occupancy of hormone receptors, (X) must be (Y)-fold greater than (Z).

A 
X = KD
Y = 10
Z = free hormone concentration

(or free hormone concentration is 1/10 of KD)

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9
Q

T/F: Nearly the full range of receptor occupancy can be obtained by varying free hormone concentration by one order of magnitude above/below KD.

A

True

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10
Q

T/F: Upon release of a hormone, the hormone-receptor interaction occurs in all tissues.

A

False - only responsive tissues (sensitive to that hormone)

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11
Q

Hormones that are derivatives of (X) are too polar to pass through (Y) and too large to pass through (Z).

A 
X = peptides and amines
Y = lipoprotein membranes (diffusion)
Z = membrane pores
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12
Q

List the two general groups of (membrane/cytoplasmic) receptors for water-soluble hormones.

A

Membrane;

  1. Serpentine (7 membrane-spanning domains)
  2. Single membrane-spanning domains
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13
Q

G-proteins are hetero-(dimers/trimers/tetramers). Alpha-subunit is a(n) (X) and is predominantly bound to (Y).

A

Hetero-trimer;
X = GTPase
Y = GDP, beta-gamma subunit, and receptor

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14
Q

Gs(alpha) is a (stimulatory/inhibitory) protein for (X), which (activates/forms/inhibits) (Y), which (activates/inhibits/forms) (Z).

A 
Stimulatory;
X = AC
Forms;
Y = cAMP (from ATP)
Activates;
Z = PKA
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15
Q

Describe the exact mechanism by which cAMP activates PKA.

A

Binds regulatory subunits and causes dissociation of active, catalytic subunits from the complex

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16
Q

T/F: PKA has multiple substrates, all of which are in the cytoplasm.

A

False - can also affect transcription of target genes in nucleus

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17
Q

Gq(alpha) (activates/inhibits) (X), which target/action?

A

Activates;
X = PLC

Cleaves PIP2 (into IP3 and DAG)

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18
Q

IP3 is formed by (X) with which function?

A

X = cleavage of PIP2

Mobilizes Ca from vesicular storage

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19
Q

DAG is formed by (X) with which function?

A

X = cleavage of PIP2

Activates PKC in the presence of Ca

20
Q

PIP2 can either be cleaved by (X) or acted on by (Y). What’s formed if (Y) acts on PIP2?

A 
X = PLC
Y = PI3K (phosphoinositol 3 kinase)

Phosphorylated into PIP3, which interacts with PDKs (kinases) and Akt

21
Q

Gi(alpha) (activates/inhibits):

A

Inhibits AC and activates K channels

22
Q

List the categories of hormone receptors that have single transmembrane domains.

A
  1. Tyr kinase
  2. Ser/Thr kinase
  3. Guanylate cyclase
  4. Cytokine
  5. MAP kinase
23
Q

Signal transduction of Tyr kinase receptors requires which steps?

A
  1. Dimerization
  2. Auto-phosphorylation of (cytoplasmic) Tyr residues
  3. Associate with/phosphorylate substrates
24
Q

Signal transduction of Ser/Thr kinase receptors requires which steps?

A
  1. Dimerization

2. Phosphorylation of Smads (cytoplasmic substrates)

25
Q

Smads are (membrane/cytoplasmic) substrates of (X) receptors. Upon activation via (Y), what is the function of Smads?

A

Cytoplasmic;
X = Ser/Thr kinase
Y = phosphorylation

Enter nucleus and influence transcription of target genes

26
Q

(X) hormones are lipid-soluble and generally act by regulating (Y) in responsive cells.

A 
X = steroid and thyroid (and vit A/D derivatives)
Y = gene expression
27
Q

Receptors for steroid hormones are located in/on (X). The first thing that occurs when hormone binds is:

A

X = in cytoplasm

Dissociation of associated proteins (which prevent inactivated receptors from interacting with DNA)

28
Q

Heat-shock proteins (i.e. HSP90) are associated with (X) receptors and function to (Y).

A 
X = steroid
Y =  prevent inactivated receptors from interacting with DNA when ligand is absent
29
Q

Steroid binds its receptor and associated protein dissociates. What’s the next step?

A

Dimerization of H-R complexes

30
Q

Steroid binds its cytoplasmic receptor and H-R dimer forms. List the next occurrences.

A
  1. Translocate to nucleus
  2. Interact with HREs (hormone response elements) on DNA
  3. Initiate/suppress transcription of nearby genes
31
Q

HREs (hormone response elements) are (X) that have one of which characteristics?

A

X = DNA sequences

  1. Palindromic sequences (inverted repeats)
  2. Direct repeats
32
Q

T/F: Steroid, thyroid, and vit D/A derivative hormone receptors are typically bound to proteins that prevent their binding to DNA.

A

False - only steroid hormones (not the others)

33
Q

Thyroid hormone receptor: the inactive receptor is associated with (X) proteins that function to (Y).

A 
X = nuclear
Y = modulate transcription of downstream genes
34
Q

Thyroid hormone receptor: upon hormone binding, (X) changes causes (dissociation/attachment) of (Y).

A 
X = conformational;
Dissociation of (Y = nuclear proteins);
AND attachment of other/different proteins
35
Q

Thyroid hormone receptor: when hormone binds, certain proteins associate with receptor and function to:

A

promote activation/suppression of transcription of target genes

36
Q

Intracellular receptors have which structural domains? Specify the function of each and star the highly conserved one(s).

A
  1. C-term: hormone binding
  2. Central: DNA binding*
  3. N-term: transcription factor recruitment
37
Q

Intracellular receptors: the central, (X)-binding domain is rich in (Y) AA residues.

A 
X = DNA
Y = Cys
38
Q

Hormone-dependent responses of cells are affected by which two factors?

A
  1. Availability of free hormone

2. Sensitivity of cells to given hormone level

39
Q

Rates of (X) processes influence the amount of circulating free hormone.

A

X = secretion, uptake, and degradation

40
Q

T/F: An increase in carrier protein concentrations results in an increase in available, biologically active steroid/thyroid hormones.

A

False - reciprocal relationship (biologically active hormones are FREE, not bound)

41
Q

List the three main factors influencing cell sensitivity to given hormone.

A
  1. Negative cooperativity
  2. Down regulation of receptors
  3. Other (i.e. uncoupling or enzyme inactivation)
42
Q

(X) is the phenomenon when binding of hormone to receptor decreases affinity of neighboring binding sites.

A

X = negative cooperativity

43
Q

Negative cooperativity may modulate hormone action by providing (high/low) cell sensitivity at (high/low) hormone concentrations.

A

High sensitivity at low concentrations and vice versa

44
Q

Uncoupling of receptor from (X) is one method that cells reduce sensitivity to hormones. This has been observed in (Y) system.

A 
X = G-protein
Y = beta-adrenergic
45
Q

T/F: Uncoupling of receptor to G-protein is done by de-phosphorylating the receptor’s cytoplasmic domains.

A

False - phosphorylating (reduces its affinity for G-protein)

46
Q

Uncoupling: high hormone concentration means (more/less) (alpha/beta/gamma) domain at cell membrane. This means the potential for (X) kinase to be bound is (greater/less), increasing chance of receptor (activation/deactivation).

A 
More;
Beta-gamma
X = beta-adrenergic receptor kinase (B-ARK)
Greater;
Deactivation

Endo/Repro (15 decks)

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