second messenger
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Transcript of second messenger
AboutSecond messengers
Dr. Yasser Ashour
By Dr.Darine Ashraf
Dr.Alaa Mamdouh
Second messengers are intracellular signaling molecules released by the cell to trigger physiological changes such as proliferation, differentiation, migration, survival, andapoptosis.
Secondary messengers are therefore one of the initiating components of intracellular signal transduction cascades.
Examples of second messenger molecules includecyclic AMP ,
cyclic GMP ,inositol trisphosphate ,diacylglycerol ,and
calcium .
The cell releases second messenger molecules in response to exposure to extracellular signaling molecules—the first messengers.
CAMP PATHWAY
Ligands : Epinephrine Ach
Primary Effector : Adenyl cyclase
Secondary messenger : cAMP
CGMP PATHWAYLigands : ANP & NO
Primary Effector : Guanylate cyclase
Secondary messenger : cGMP
CALCIUM AS SECOND MESSENGERCalcium ions – once they enter the cytoplasm exert allasteric regulatory effects on many enzymes & protien.
Calcium acts as a second messenger by indirect signal transduction pathways such as via G protein – coupled receptors.
EICOSANOIDSThis class of llipids act as signaling molecules that binds to cell surface molecules.
They include: Prostaglandins
Prostacyclin Thromboxanes
Leukotrienes
GENERAL SCHEMATIC OF SECOND MESSENGER MECHANISM