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I will discuss signal transduction mechanism today.
All cells receive and respond to signals.
The signaling molecules are of various types and their receptors are also different, the receptors can also vary from cell to cell in same organism in different location.
Four types of signals are there:
1.Endocrine: act over very long distance and carried through circulatory system, eg. Hormones.
2.Paracrine: act locally on nearby cells, highly unstable, eg. NO, neurotransmitters etc.
3.Juxtacrine:also to very short distance, require physical contact of cells.
4.Autocrine:the signal produce by cell act on the same cell which produces the signal.
Types of signals
I will discuss signal transduction mechanism today.
All cells receive and respond to signals.
The signaling molecules are of various types and their receptors are also different, the receptors can also vary from cell to cell in same organism in different location.
Four types of signals are there:
1.Endocrine: act over very long distance and carried through circulatory system, eg. Hormones.
2.Paracrine: act locally on nearby cells, highly unstable, eg. NO, neurotransmitters etc.
3.Juxtacrine:also to very short distance, require physical contact of cells.
4.Autocrine:the signal produce by cell act on the same cell which produces the signal.
Types of signals
1. Steroids and steroidal hormones: small hydrophobic molecules which can diffuse through plasma membrane, their receptor are intracellular protein. (All the receptors of them are part of single superfamily called nuclear recepter superfamily).
2. Gaseous signals: NO, CO. They act locally on nearby cells, paracrine. They directly act on enzymes and modulate their activity.
Arginine is precursor of NO. Nitric oxide synthase( NOS) enzyme is required for NO production in animals. In plants nitric oxide synthase is absent so nitrate reductase synthesize it.
Action of NO: Acetyl choline released in endothelial cells (on stimulus)activates NOS which produces NO, it diffuses out and act on guanyl cyclase enzyme and activates it. Guanyl cyclase produces cGMP which causes muscle to relax and in turn vessel dilates.
CO is analogous to NO. It is very important signal in nervous system.It can also synthesize cGMP.
3. Neurotransmitters: convey signals between neurons, they are basically hydrophillic. They are produce on stimulus.Targets of neurotransmitters are ion channels, ligand gated, some targets are G protein coupled receptors.
4.Peptides and growt factors:includes peptides, polypeptides, growth hormones, neuropeptides.
5.Eicosanoids: these are certain lipids for which receptors are present on plasma membrane. These include prostaglandins, leukotrienes, thromboxanes etc.
2. Gaseous signals: NO, CO. They act locally on nearby cells, paracrine. They directly act on enzymes and modulate their activity.
Arginine is precursor of NO. Nitric oxide synthase( NOS) enzyme is required for NO production in animals. In plants nitric oxide synthase is absent so nitrate reductase synthesize it.
Action of NO: Acetyl choline released in endothelial cells (on stimulus)activates NOS which produces NO, it diffuses out and act on guanyl cyclase enzyme and activates it. Guanyl cyclase produces cGMP which causes muscle to relax and in turn vessel dilates.
CO is analogous to NO. It is very important signal in nervous system.It can also synthesize cGMP.
3. Neurotransmitters: convey signals between neurons, they are basically hydrophillic. They are produce on stimulus.Targets of neurotransmitters are ion channels, ligand gated, some targets are G protein coupled receptors.
4.Peptides and growt factors:includes peptides, polypeptides, growth hormones, neuropeptides.
5.Eicosanoids: these are certain lipids for which receptors are present on plasma membrane. These include prostaglandins, leukotrienes, thromboxanes etc.
The precursors is arachidonic acid which is derived from phospholipid.
6.Plant hormones: auxin, gibberlin, cytokinin,etc.
will continue ..
Hope this will help you all. See you all with next topic.
Thankyou for reading.
6.Plant hormones: auxin, gibberlin, cytokinin,etc.
will continue ..
Hope this will help you all. See you all with next topic.
Thankyou for reading.
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