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Hücre içi sinyal iletiminin özet anlatımı.
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Hücrede Sinyal İletimiHücrede Sinyal İletimi
Nefize Ezgi Altınışık2601110400
ÇeşitleriÇeşitleri
• Temas bağımlı sinyal iletimi• Parakrin sinyal iletimi• Sinaptik Sinyal iletimi• Endokrin sinyal iletimi
Salgı Sinyalleri
(a) Paracrine signaling. A secreting cell acts on nearby target cells by discharging molecules of a local regulator (a growth factor, for example) into the extracellular fluid.
(b) Synaptic signaling. A nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell.
Local regulator diffuses through extracellular fluid
Target cell
Secretoryvesicle
Electrical signalalong nerve celltriggers release ofneurotransmitter
Neurotransmitter diffuses across
synapse
Target cellis stimulated
Local signaling
Figure 11.4 A B
Hormone travelsin bloodstreamto target cells
(c) Hormonal signaling. Specialized endocrine cells secrete hormones into body fluids, often the blood. Hormones may reach virtually all body cells.
Long-distance signaling
Bloodvessel
Targetcell
Endocrine cell
Figure 11.4 C
EXTRACELLULARFLUID
Receptor
Signal molecule
Relay molecules in a signal transduction pathway
Plasma membraneCYTOPLASM
Activationof cellularresponse
Figure 11.5
Reception1 Transduction2 Response3
YanıtlarYanıtlar
• Hayatta kalma• Büyüme ve Bölünme• Farklılaşma• Ölüm
Yanıtlar hızlı ya da yavaş olabilir.
Cross-talk (Çapraz Cross-talk (Çapraz Yanıt)Yanıt)
Response 1
Response 4 Response 5
Response
2
Response
3
Signalmolecule
Cell A. Pathway leads to a single response
Cell B. Pathway branches, leading to two responses
Cell C. Cross-talk occurs between two pathways
Cell D. Different receptorleads to a different response
Activationor inhibition
Receptor
Relaymolecules
Figure 11.15
ReseptörleReseptörlerr
G-protein-linkedReceptor
Plasma Membrane
EnzymeG-protein(inactive)CYTOPLASM
Cellular response
Activatedenzyme
ActivatedReceptor
Signal molecule Inctivateenzyme
Segment thatinteracts withG proteins
GDP
GDP
GTP
GTP
P i
Signal-binding site
Figure 11.7
GDP
G Proteini Bağlı Reseptörler
ReseptörlerReseptörlerSignalmolecule
Signal-binding sitea
CYTOPLASM
Tyrosines
Signal moleculeHelix in the
Membrane
Tyr
TyrTyr
TyrTyr
TyrTyr
TyrTyr
TyrTyr
Tyr
Tyr
TyrTyr
TyrTyr
Tyr Tyr
TyrTyr
TyrTyr
Tyr
Tyr
TyrTyr
TyrTyr
Tyr
DimerReceptor tyrosinekinase proteins(inactive monomers)
PPP
PP
P Tyr
TyrTyr
TyrTyr
TyrP
PP
PP
PCellularresponse 1
Inactiverelay proteins
Activatedrelay proteins
Cellularresponse 2
Activated tyrosine-kinase regions(unphosphorylateddimer)
Fully activated receptortyrosine-kinase(phosphorylateddimer)
6 ATP 6 ADP
Figure 11.7
Protein Kinaz Reseptörleri
ReseptörlerReseptörler
Cellularresponse
Gate open
Gate close
Ligand-gatedion channel receptor
Plasma Membrane
Signalmolecule(ligand)
Figure 11.7
Gate closed Ions
İyon Kanalı Reseptörleri
Reseptörlerin Reseptörlerin mekanizmalarımekanizmaları
Signal molecule
Activeproteinkinase
1
Activeproteinkinase
2
Activeproteinkinase
3
Inactiveprotein kinase
1
Inactiveprotein kinase
2
Inactiveprotein kinase
3
Inactiveprotein
Activeprotein
Cellularresponse
Receptor
P
P
P
ATPADP
ADP
ADP
ATP
ATP
PP
PP
PP
Activated relaymolecule
i
Phosphorylation cascade
P
P
i
i
P
Fosforilasyon
Reseptörlerin Reseptörlerin mekanizmalarımekanizmaları
G proteini bağlanması
ATP
GTP
cAMP
Proteinkinase A
Cellular responses
G-protein-linkedreceptor
AdenylylcyclaseG protein
First messenger(signal moleculesuch as epinephrine)
İkincil İkincil HabercilerHaberciler
• Protein olmayan, küçük moleküller• Reseptörlerin aktifleşmesinde,
sinyalin iletilmesinde rol oynarlar.
– cAMP– Kalsiyum– İnositil trifosfat– Diaçilgliserol
PKA PKA AktivasyonuAktivasyonu
321
IP3 quickly diffuses throughthe cytosol and binds to an IP3–gated calcium channel in the ERmembrane, causing it to open.
4 The calcium ionsactivate the nextprotein in one or moresignaling pathways.
6 Calcium ions flow out ofthe ER (down their con-centration gradient), raisingthe Ca2+ level in the cytosol.
5
DAG functions asa second messengerin other pathways.
Phospholipase C cleaves aplasma membrane phospholipidcalled PIP2 into DAG and IP3.
A signal molecule bindsto a receptor, leading toactivation of phospholipase C.
EXTRA-CELLULARFLUID
Signal molecule(first messenger)
G protein
G-protein-linkedreceptor
Variousproteinsactivated
Endoplasmicreticulum (ER)
Phospholipase CPIP2
IP3
(second messenger)
DAG
Cellularresponse
GTP
Ca2+
(second messenger)
Ca2+
IP3-gatedcalcium channel
Sinyal Sinyal ÇoğaltımıÇoğaltımı
Glucose-1-phosphate(108 molecules)
Glycogen
Active glycogen phosphorylase (106)
Inactive glycogen phosphorylase
Active phosphorylase kinase (105)
Inactive phosphorylase kinase
Inactive protein kinase A
Active protein kinase A (104)
ATP
Cyclic AMP (104)
Active adenylyl cyclase (102)
Inactive adenylyl cyclase
Inactive G protein
Active G protein (102 molecules)
Binding of epinephrine to G-protein-linked receptor (1 molecule)
Transduction
Response
Reception
HedeflerHedefler
• Gen anlatımı düzenleyicileri• Enzimler• Yapısal proteinler
Yavaş Yanıtlar
• Gen anlatımı üzerinde etkililerReception
Transduction
Response
mRNANUCLEUS
Gene
P
Activetranscriptionfactor
Inactivetranscriptionfactor
DNA
Phosphorylationcascade
CYTOPLASM
Receptor
Growth factor
Sinyal Sinyal KompleksleriKompleksleri
• Scaffold Proteinleri
Signalmolecule
Receptor
Scaffoldingprotein
Threedifferentproteinkinases
Plasmamembrane
Figure 11.16
RAS-MAPK RAS-MAPK YolağıYolağı
RAS Aktivasyonu
RAS-MAPK RAS-MAPK YolağıYolağı
MAPK Aktivasyonu
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