CATALYTIC RECEPTORS-Ser/Thr kinase receptors and their types

1. CATALYTIC RECEPTORS:
SERINE-THREONINE KINASE RECEPTORS
AND THEIR TYPES
SUPRIYA S D S
Dept of Crop Physiology
GKVK,UAS BENGALURU
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2. TYPES OF RECEPTORS IN CELL SIGNALLING
1
2
3
4
https://www.ncbi.nlm.nih.gov/books/NBK10989/figure/A546/?report=objectonly
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3. 1
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http://membranereceptors.com/Test2/wp-content/uploads/2013/07/Enzyme-linkedreceptors1.jpg

4. There are six main types of enzyme-linked receptors:
Classification
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( Alberts et al., 2002)

5. TYPES OF SERINE-THREONINE KINASE
RECEPTORS (Mammalian system)
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(Alexander et al., 2015)
Growth and immune responses:
Cell differentiation, proliferation, immune suppression, wound healing

6. TYPE I Serine/threonine receptor kinases
The type I receptor serine/threonine kinases are also known as activin
receptors or activin receptor-like kinases, ALKs, for which a systematic
nomenclature has been proposed (ALK1-7).
2
TYPE II Serine/threonine receptor kinases
The type II receptor serine/threonine kinases consist of five members:
Activin Receptor Type 2A, Activin Receptor Type 2B, BMP Receptor Type
2, TGF-β receptor Type 2 and Anti-Mullerian Hormone Receptor Type 2.
3 TYPE III Serine/threonine receptor kinases
Type III receptors, sometimes called co-receptors or accessory proteins,
regulate the signalling of the receptor complex in either enhancing (for
example, presenting the ligand to the receptor) or inhibitory manners.
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7. 1
2
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8. Receptor Serine/Threonine Kinase:
https://doi.org/10.1371/journal
Receptor Ser/Thr kinases (RSTK) respond to particular cytokines, TGF-β
(Transforming Growth Factor-β) and BMP families (Bone Morphogenesis
Protein)
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doi: 10.1101/cshperspect.a022111
NOTE
These receptors phosphorylate transcription factor Smad proteins
in response to extracellular growth factors including TGF-β,
activins, inhibins, nodal and Bone Morphogenic Proteins (BMPs).
SMAD: SMA and MAD genes

9. SIGNALING
MECHANISM
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BUB1- A Ser/Thr kinase as a key mediator in TGF-β signaling
(Nyati et al., 2015)
BUB1-Budding Uninhibited by Benzimidazoles-1 EMT-Epithelial mesenchymal
transition, a process by which
epithelial cells lose their cell
polarity and cell-cell adhesion
and gain migratory and invasive
properties

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Whether BUB1 physically interacts with TGFβR1
Colocalization using TIRF microscopy
(total internal reflection fluorescence)
BUB1 inhibitors
(Immunohistochemical staining)
After 72 hrs of treatment with TGF-β,
the proportion of colocalised BUB1
and TGFBR1 signals doubled
Decreased abundance of
phosphorylated SMAD2

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(Afzal et al., 2008)
TYPES OF SERINE-THREONINE KINASE
RECEPTORS (In Plants)

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RLKs in Plants
Role RLKs Function
Plant pathogen
response and
defense
FLS2
EF-Tu
Flagellin recognition, a bacterial elicitor
Growth and
Development
NORK
SYMRK
BRI1
CR4
EMS1
SCM
CLV1
Perception of a lipopolysaccharide nodulation signal
Rhizobial symbiosis
Cell de-differentiation and proliferation
Development of epidermal leaf cells and endosperm
surface in maize
Development of tapetal cell layer
Root hair cell patterning
Regulation of meristem size
(Morillo and Tax, 2006)

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CONCLUSION:CONCLUSION:
RSTK type of receptors form the TGF-β superfamily of receptors in
mammalian system, whereas incase of plants, they form IRE-Like and RLK
family of receptors.
 They regulate various growth, development and disease related responses
both in plants and animals.
 In mammalian system, TGF-β receptors modulate their responses through
smad proteins.
 BUB1 –a kinase protein as the key mediator in TGF-β signaling.
 In plants, they form a large protein family of Receptor like kinases (RLKs)
and are known to be involved in the regulation of growth, differentiation and
immune responses to pathogen.