g-protein coupled receptors(gpcr)

7/24/2019 G-protein Coupled Receptors(Gpcr)

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Moderator:

Dr Mohan Amberkar

G-PROTEIN COUPLED

RECEPTORS(GPCR)


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Introduction

StructureClassifcationActivation and inactivationStructure and role o G-proteins

Classifcation o G-proteinsTarets o G-proteins

-Aden!l!l c!clase

-"hospholipase C

-Ion channels -#ho A$#ho kinase

-MA" kinase#ecent developments in G"C# biolo!Conclusion#erences

PROTOCOL

%


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&rian 'obilka and #obert (eko)it*

+crucial or understandin ho) G"C#unction,

Cell surace proteinsMaor class o dru tarets

.-TM receptors/0eptahelicalreceptors/Serpentine receptors/G"(#1s22

G"C# amil!Senses the outside molecules and activates

inside the sinal trasduction path)a!cellular responses2

INTRODUCTION

3


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&eta adrenoreceptor in 4567

All the receptors identifed have no) been cloned

Aspirin receptor has to be cloned

Charecteristic structure:

- . transmembrane alpha helices - e8tracellular 9-terminal

- intracellular C-terminal

STRUCTURE


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;


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7


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Family Receptors Structural Features

A: Rhodopsin family -Thelargest group.

- Receptors for most amine

neurotransmitters, many

neuropeptides, purines,

prostanoids, cannabinoids, etc.

-Shortextracellular (N terminal)

tail.

-Ligand binds to transmembrane

helices (amines) or to extracellular

loops (peptides)

B: Secretin/Glucagon receptor

family

Receptors for peptide hormones,

including secretin, glucagon,

calcitonin,gastrin,CC,leptin etc

-Intermediateextracellular tail

incorporating ligand-binding

domain

C: Metabotropic glutamate

receptor/calcium sensor family

-Smallestgroup

-!etabotropic glutamate receptors,

"#$#$receptors, Ca%&-sensing

receptors

-Longextracellular tail

incorporating ligand-binding

domain

Others :D: ungal mating pheromonereceptors

!: Camp receptors

: ri""led/smoothened

receptors .


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Glutamate receptor amil!

#hodopsin receptor amil!

Adhesion receptor amil!


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Sinle site mutaenesis liand mappin

desin s!nthetic

liands

X ray crystallography-molecular structureo G"C#1s

Fluorescence methods-kinetics o liandbindin

4=


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Aonist bindin"rotease activated receptors>"A#1s?

- thrombin snips o the 9-terminal tail

TET#ERED GONIST

Activation o "A#1s

"A# molecule can be activated onl! once

$et%o&s o' ctiatio"

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INCTITION


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GT" GD"?

G Protein

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Consists o 3 subunits-alpha/beta and amma

Alpha subunit:

-Guanine nucleotide binds to the alpha

subunit -0as en*!matic activit!

Beta and gamma subunit:

-#emain toether as a comple8

Anchored throuh an alpha att! acid chainBPREN*LTION+


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SU,T*PE SSOSITED RECEPTORS $IN EFFECTORS


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SU,T*PE SSOSITED RECEPTORS $IN EFFECTORS

Gs Man! amine and other receptors>e22 catecholamines/ histamine/serotonin?

Stimulates aden!l!l c!clase/ causinincreased cAM" ormation

Gi As or Gs/ also opioid/ cannabinoid

receptors

Inhibitsaden!l!l c!clase/ decreasincAM" ormation

Go As or Gs/ also opioid/ cannabinoid

receptors

(imited eects o subunit >eectsmainl! due to EF subunits?

G Amine/ peptide and prostanoidreceptors

Activates phospholipaseC/ increasinproduction o second messenersinositol trisphosphateanddiac!ll!cerol

GEF subunits

All G"C#s Activate potassium channelsinhibit voltae-ated calciumchannelsactivate G"C# kinasesactivate mitoen-activated proteinkinase cascade

4.


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#eceptor and e@ector selectivit!

Molecular variations )ithin the alpha subunits

Specifc reconition domains

en*!mes?

Cholera to8in "ertussis to8in

SPECIFICITY

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Cholera to8in

Acts onl! on Gs

"ersistent activation

S!mptoms o cholera

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"ertussis to8in

&lock Giand Go

"revents Gi to bind to aden!l!l c!clase

Increases cAM"

%=


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Activation o G"C#

Conormational chane in the receptor

Assosiaton o G-protein )ith the receptor

GD"-GT" e8chane

Dissosiation o the trimer

Active orms o G-protein

Di@use and assosiate )ith various en*!mes and ions channels

Activation o TA#GHT$H


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4? Aden!l!l c!clase

%? "hospholipase C

3? Ion channels

? #ho A$#ho kinase;? Mitoen-activated protein kinase>MA"

kinase?

Tarets 'or G-protei"s

%%

l l l


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Sutherland and his colleaues

+second messeners in sinal transduction,

AT" cAM" ;AM"

There are 5 di@erent molecular isoorms oaden!l!l c!clase2

e"ylyl cyclase.c$Psystem

AC "DH1s

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cAM"

"rotein kinases

Jarious e@ects

Celldivision

Celldi@erentiatio

n

Iontranspo

rt

Ionchannels

Contractile

proteins

Hner!

metabolism

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%;


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cAM"

"rotein kinase

Increase activit! o voltae ated calcium channels in heartmuscle cells

"hosphor!lation o these channels

Increase calcium entr!

Increasin the orce o contraction o the heart

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cAM"

"rotein kinases

Inactivation o m!osin liht chain kinase

Smooth muscle rela8ation

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cA!P

Decrease I"crease

M% receptor o 42 "DH?

pioid receptors 2 Milrinone>"DH3?

;2Sildenafl>"DH;?

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In 45;=1s b! 0okin and 0okin

Michell and &erride

- Increase in ree Ca increase "I

turnoverEg:

- muscarinic aonists

- alpha aonists actin on smooth musclesand salivar! lands

- vasopressin actin on liver cells

"I"%/member o "I amil!/ pla!s a ke! role

P%osp%olipase C.I"ositolp%osp%ate system

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3=


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G"C# can act on ion channels directl!orindirectl!

Direct G-protein channel interaction )as frst

sho)n on cardiac muscleH: - mACh#s enhances 'L permeabilit!

- In neurons/ opioid analesics

open 'L channels inhibit Cachannels

ION C#NNELS

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Activated b! certain G"C#1s )hich couple to the G-proteinso G4%$43t!pe2


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Activated b!:

- c!tokines

- ro)th actors

- G"C# liands

Hnd result cell prolieration

"rovin to be a pathoenic path)a! or cancer

Man! compounds inhibitin this path)a!

potential anti cancer drus

H: Soraenib/ dabraenib and vemuraenib #akinase

Selumetinib/ trametinib MH' inhibitors

$P 0i"ase system

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Involves % main processes:

- receptor phosphor!lation

- receptor internalisation>endoc!tosis?

#esidues in the C-terminal c!toplasmic tailets phosphor!lated

Involvement o protein kinase A/protein kinaseC and G"C# kinases

DESENSITISTION

3


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3;

Rece"t &eelopme"ts i"


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GPC" dimerisation#

GA&Ab #4

H:GA&A b

GA&Ab #%

- Dopamine %

-Somatostatin receptors

Constitute$ely acti$e receptors:

- &eta adrenoreceptor:mutation in the 3rdintracellular loop or overe8pression o the receptor2

-0istamine>03? sho)s constitutive activit! in vivo2

Rece"t &eelopme"ts i"GPCR

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"eceptor acti$ating modi%yingproteins&"A!P's(#

- amil! o membrane proteins that associate)ith G"C# and alter the unctional

characteristics2H:

- 9europeptide CG#"NC#(#>G"C#? L #AM" 4

- Adrenomedullin N C#(#>G"C#? L #AM" %

3.


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"egulators o% G)protein Signalling&"GS(


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Cell penetratin peptides

Acts as intracellular modulators o sinal transmission rom aG"C# to G-proteins2

#O1 IT CTS22

It utili*es the lipid raments o intracellular G"C# loops tomodulate the G"C# action2

1#ERE IT CTS22

Anchorin to the lipid bi-la!er and thereb! taretin the interace

"epducins or over 4; di@erent G"C#1s have been successull!produced

Ananti "A# pepducin-e8tendedbleedin time in mice andprotected aainst platelet activation and thrombosis

A COC# aonist pepducin mobil*es hematopoetic stem cells tobone marro)

PEPDUCINS

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C*+C,-SI*+

=


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42 #an 0"/Dale MM/#itter PM/?244;5%=2

32 &arnadUttir T'/ Gloriam DH/ 0ellstrand S0/ 'ristiansson 0/ September %==7?2 Comprehensive repertoire and

ph!loenetic anal!sis o the G protein-coupled receptors in human andmouse2 Genomics33>3?: %73.32

2 Tressel S(/ 'oukos G/ Tchern!chev &/ Pacues S(/ Covic (/ 'uliopulos A>%=44?2 "harmacolo!/ biodistribution/ and eWcac! o G"C#-basedpepducins in disease models2 Methods in Molecular Biology (Clifton,N.J.)2 Methods in Molecular &iolo! 536: %;5.;

;2 Dimond "/ Carlson '/ &ouvier M/ Gerard C/ Ou (/ Covic (/ Aar)al A/ Hrnst"/ Pan* PM/ Sch)art* TR/ Gardella TP/ Millian G/ 'uliopulos A/ Sakmar

T"/ 0unt SR >Ma! %=44?2 G protein-coupled receptor modulation )ithpepducins: movin closer to the clinic2Annals of the New or! Academyof "ciences7885: 35

4

#erences


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72 "enela "/ #ibas C/ Ma!or < >9ovember %==3?2Mechanisms o reulation o the e8pression and unctiono G protein-coupled receptor kinases2 Cell."ignal.74>44?: 5.3642

.2 (uttrell (M/ (eko)it* #P >


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g-protein coupled receptors(gpcr)

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