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Vydehi veeramallaFinal yr pgDepartment of Biochemistry
CONTENTS
CELL SIGNALLING
TYPES OF SECOND MESSENGERS
CHARECTERISTICS OF SECOND MESSENGERS
HORMONES ACTING THROUGH CYCLIC AMP
MECHANISM OF ACTION OF CYCLIC AMP
EFFECTS OF CYCLIC AMP
HISTORYEarl Wilbur Sutherland Jr. – 1971 Nobel Prize in
Physiology or Medicine
Epinephrine – liver - glycogen to glucose – cAMP
INTRODUCTION
Cyclic AMP is a cyclic nucleotide
Chemically it is a 3’5’ adenosine monophosphate
It is synthesized in tissues from ATP under influence of ADENYLYL CYCLASE in presence of Mg ion
Degraded to 5’AMP in by Phosphodiesterase
It is a Second Messenger
cell signaling- 3 processes
A series of signaling events that mediate the response to each stimulus.
specific
amplified
regulated
coordinated.
receptors plasma membrane , cytoplasm or nucleus.
Second Messengers
cAMP pathway
cGMP pathway
IP3 / DAG pathway
Calcium as a second messenger
Eicosanoids
Second Messengers
General characteristics1) Low amounts in resting state
2) Regulated synthesis
3) Regulated destruction
4) Act through other proteins
hCGLHFSHLPH PTHCALCITON
IN
Epinephrine (β1,β2)NorepinephrineGlucagonCRHACTHMSH TSH
1.Somatostatin
2.Acetylcholine M2
3.Angiotensin II
4.Epinephrine α2
ATIVATE ADENYLYL CYCLASE
INHIBIT ADENYLYL CYCLASE
AVP/ADH
G Protein-Linked Receptors
G-PROTEIN COUPLED RECEPTOR
tes
Activation of G Proteins
AC
ADENYLYL CYCLASE
G PROTEIN ACTIVATES ADENYLYL CYCLASE
Cyclic AMP
PROTEIN KINASE A - ACTIVATION
EFFECTS OF CYCLIC AMP1. ALTERED GLYCOGEN METABOLISM BY ENZYME REGULATION
2. ALTERED GENE TRANSCRIPTION
3. HORMONE ESTRADIOL SECRETION
4. ALTERED ION TRANSPORT - HCL SECRETION IN STOMACH
5. WATER REABSORPTION BY ANTI DIURETIC HORMONE
6. CAFFEINE – PHOSPHODIESTERASE INHIBITORS
7. DRUGS – SALBUTAMOL , THEOPHYLLINE
ENZYME REGULATION
GSD VIII,IX GSD X
GENE TRANSCRIPTION
TRANSCRIPTION FACTOR COACTIVATOR
ESTRADIOL SECRETION
STOMACH - HCL SECRETION
HISTAMINE
KIDNEY - WATER REABSORPTION
ANTIDIURETIC HORMONE
PHOSPHODIESTERASE INHIBITORS
EPINEPHRINE NOREPINEPHRINE SALBUTAMOL
DRUGS
THEOPHYLLINEPDE
Summary
Cyclic amp is a mediator of hormone actionSecond messengerActivates protein kinase A
Causes glycogenolysis Causes lipolysisModulates TranscriptionActivates Hormone secretionIncreases gastric secretionRegulates cell permeability to water
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