Hi All
To continue with signal transduction...
Signal cGMP
GTP is converted to cGMP by enzyme guanyl cyclase. NO,CO gases activates guanyl cyclase.
In the retina rhodopsin is linked to G protein. Rhodopsin is G protein coupled receptor and is part of rod cells of retina.
The G alpha protein of rhodopsin are called transducin.
Initially rhodopsin has 11 cis retinal molecule.
When light falls on retina, the 11 cis retinal is converted to all transretinal.
It changes the conformation of receptor opsin and G alpha or transducin dissociates and binds to cGMP phophodiesterse.
Phosphodiesterse breaks cGMP.
Decrease in the level of cGMP in rod cells initiates a nerve impulse. Since cGMP acts on sodium channels in plasma membranes of neurons, the sodium channels get closed in response to decrease in cGMP level.
So basically the role of CGMP is conversion of visual signal into electrical stimulus.
Point to be noted here is I have not discussed the dissociation of alpha beta nad gamma of G protein as already discussed in earlier blog.
JAK/STAT pathway or Janus Kinase pathway
This is very short and very fast pathway which directly involves interaction with transcription factors with receptors on membrane.
It is cytokine receptor pathway.
STAT signal transducers and activators of transcription.
When the cytokine binds the receptor it dimerises and recruit STAT on both at cytosolic domain.
JAK are cytosolic kinase on cytosolic sides of receptor dimer.
As STAT are recruited JAK phosphorylate STAT ad STAT after phosphorylation released from JAK and form STAT dimer in cytoplasm.STAT dimer's nuclear localising signal is exposed as they dimerise and now they can go to nucleus.
They pass to nucleus and interact with genes and cause change in gene expression.
Thankyou for reading.
To continue with signal transduction...
Signal cGMP
GTP is converted to cGMP by enzyme guanyl cyclase. NO,CO gases activates guanyl cyclase.
In the retina rhodopsin is linked to G protein. Rhodopsin is G protein coupled receptor and is part of rod cells of retina.
The G alpha protein of rhodopsin are called transducin.
Initially rhodopsin has 11 cis retinal molecule.
When light falls on retina, the 11 cis retinal is converted to all transretinal.
It changes the conformation of receptor opsin and G alpha or transducin dissociates and binds to cGMP phophodiesterse.
Phosphodiesterse breaks cGMP.
Decrease in the level of cGMP in rod cells initiates a nerve impulse. Since cGMP acts on sodium channels in plasma membranes of neurons, the sodium channels get closed in response to decrease in cGMP level.
So basically the role of CGMP is conversion of visual signal into electrical stimulus.
Point to be noted here is I have not discussed the dissociation of alpha beta nad gamma of G protein as already discussed in earlier blog.
JAK/STAT pathway or Janus Kinase pathway
This is very short and very fast pathway which directly involves interaction with transcription factors with receptors on membrane.
It is cytokine receptor pathway.
STAT signal transducers and activators of transcription.
When the cytokine binds the receptor it dimerises and recruit STAT on both at cytosolic domain.
JAK are cytosolic kinase on cytosolic sides of receptor dimer.
As STAT are recruited JAK phosphorylate STAT ad STAT after phosphorylation released from JAK and form STAT dimer in cytoplasm.STAT dimer's nuclear localising signal is exposed as they dimerise and now they can go to nucleus.
They pass to nucleus and interact with genes and cause change in gene expression.
Thankyou for reading.
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