Signaling-1

Question 1

Enumerate features of signal tranduction system

Answer 1

1. Specificity
2. Amplification
3. Desensitization & adaptation
4. Integration

Question 2

Main functional Domains of hormone receptors are…..&…..

Answer 2

Recognition domain & coupling domain

Question 3

Classify receptors

Answer 3

A) Intracellular receptors: nuclear (thyroid, calcitriol, female hormones) or cytoplasmic (glucocorticoids & aldosterone)
B) Cell-membrane receptors:
1. Serpentine (use adenyl cyclase as beta receptors OR phospholipase C as alpha-1 receptors
2. Receptors with intrinsic enzymatic activity (with guanylyl cyclase as ANP OR tyrosine kinase fas insulin/growth factors)
3. Receptors that lack enzymatic activity (JAK-STAT cascade of GH)
4. Ion channel receptors

Question 4

Mention hormones derived from tyrosineu

Answer 4

CAs(DA,EP,NE), T3,T4

Question 5

Eicosanoids are derived from….., they include……

Answer 5

Arachidonic acid (20C PUFA)
Prostaglandins, TXA, leukotrienes

Question 6

GR: Lipophilic hormones have prolonged half-life

Answer 6

Associate with plasma transport (carrier) proteins as they are insoluble in the aqueous medium if plasma

Question 7

Describe mechanism of signal transduction for lipophilic hormones

Answer 7

1. They readily traverse lipophilic plasma membrane and bind cytosol or nucleus of target cells
2. They bind to intracellular receptors to form horomone-receptor complex
3. This causes conformational change so it can bind with high affinity to specific DNA sequence called HRE which either enhance or suppress transcription

Question 8

Enumerate domains of lipophilic hormone receptors

Answer 8

1. Carboxyl terminal binding hormone
2. DNA binding domain (contain zinc finger motifs)
3. Amino terminal acting as gene enhancer or suppressor