Hello Friends
To continue with signal tranduction.
free life science study material. Types of receptors.
1. G protein coupled receptors: Largest family of receptors.
These are GTP coupled proteins and transmembrane protein.This receptor have 7 transmembrane segments alpha helical in nature.
G protein has three subunits alpha , beta and gamma (heterotrimeric).
GTP/GDP binding sites are present on alpha subunits.
When ligand bind the receptor the GDP gets exchanged with GTP on G alpha subunit.
When GTP binds to alpha the affinity of alpha decreases for beta and gamma and is free to interact with target.
Beta and gamma can also act as signals.
2. Protein tyrosine kinase receptor: are directly linked to enzyme activity.
It has three subunits: N terminus which is ligand binding site, transmembrane segment and C terminus which is cytosolic and has intrinsic tyrosine kinase activity.
When ligand bind to N terminus it causes dimerization of receptor.(ligand can be monomer or dimer).
After dimerization the kinase activity of C terminal gets activated and cross phosphorylates the opposite C Terminal and then autophosphorylation takes place.The protein that can bind to phosphorylated tyrosine are :
a) Which have SH2 (src homology) domain and
b) Which have PTB (phosphotyrosine binding domain). Either of them can bind to activated protein tyrosine kinase receptor.
3. Cytokine receptor: Similar to tyrosine kinase receptor. The only difference is it does not have intrinsic tyrosine kinase activity.
When ligand bind it causes dimerization and affinity for cytosolic kinase increases. The cytosolic kinase bind to c terminal and cross phosphorylate and become active.
4. Other receptors include receptor associated with tyrosine phosphatase, serine or threonine kinase and receptor associated with guanyl cyclase.
Secondary messanger will be discussed in next blog.
Thankyou.
To continue with signal tranduction.
free life science study material. Types of receptors.
1. G protein coupled receptors: Largest family of receptors.
These are GTP coupled proteins and transmembrane protein.This receptor have 7 transmembrane segments alpha helical in nature.
G protein has three subunits alpha , beta and gamma (heterotrimeric).
GTP/GDP binding sites are present on alpha subunits.
When ligand bind the receptor the GDP gets exchanged with GTP on G alpha subunit.
When GTP binds to alpha the affinity of alpha decreases for beta and gamma and is free to interact with target.
Beta and gamma can also act as signals.
2. Protein tyrosine kinase receptor: are directly linked to enzyme activity.
It has three subunits: N terminus which is ligand binding site, transmembrane segment and C terminus which is cytosolic and has intrinsic tyrosine kinase activity.
When ligand bind to N terminus it causes dimerization of receptor.(ligand can be monomer or dimer).
After dimerization the kinase activity of C terminal gets activated and cross phosphorylates the opposite C Terminal and then autophosphorylation takes place.The protein that can bind to phosphorylated tyrosine are :
a) Which have SH2 (src homology) domain and
b) Which have PTB (phosphotyrosine binding domain). Either of them can bind to activated protein tyrosine kinase receptor.
3. Cytokine receptor: Similar to tyrosine kinase receptor. The only difference is it does not have intrinsic tyrosine kinase activity.
When ligand bind it causes dimerization and affinity for cytosolic kinase increases. The cytosolic kinase bind to c terminal and cross phosphorylate and become active.
4. Other receptors include receptor associated with tyrosine phosphatase, serine or threonine kinase and receptor associated with guanyl cyclase.
Secondary messanger will be discussed in next blog.
Thankyou.
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