Ion channel receptors turn chemical signals into electrical signals
GPCR
GPCR is structurally a monomer protein, extracellular amino acid, intracellular carboxyl terminal; its peptide chain repeatedly spans the membrane seven times, also known as the second transmembrane receptor
The signal transfer path basic mode is the same
The cAMP-PKA pathway
Regulates the metabolism
Regulates the gene expression
Regulates the cell activity
The IP3/DAG-PKC pathway
Ga2 + regulates the protein-dependent protease pathway
GPCR causes an increase in the intracellular Ga2 + concentration
Certain G proteins directly activate the calcium channels on the cell membrane
The cytoplasmic membrane calcium channel is activated through PKA to promote the Ga2 + influx
Release of Ga2 + in the cytoplasmic calcium reservoir through IP3+
Enzyme-coupled receptor
Signal pass mainly through protein modification or interactions
Most are single transmembrane receptors
eg:Ras/MAPK pathway
Specific receptors
Intracellular receptors: The corresponding ligands are lipid-soluble signaling molecules
Membrane receptor: The corresponding ligands are water-soluble signal molecules and membrane-binding signal molecules
Extracellular chemical signals
As the first messenger
Soluble molecules: Between cells as free molecules
fat-soluble
water-solubility
internal secretion
paracrine secretion
neurotransmitter
Membrane-binding signaling molecules: Intercellular contact is required to transmit signals
Intracellular signal transduction molecules
The second messenger binds to and activates the downstream signal transduction molecules
Small molecular messengers transmit a signal
cAMP(cyclic nucleotide) is the most important intracellular second messenger
The upstream signaling transduction molecules of cAMP and cGMP are the corresponding nucleotide cyclases
Phosphoipdiesterase catalyzes the hydrolysis of cyclic nucleotides
Cycloucleotides regulate protease activity within cells
Protein kinases are not the only target molecules of cAMP and cGMP
Lipid classes can also derive an intracellular second messenger
Phosphatidyinositase and phospholipase catalyze the birth of a second messenger
The lipid second messenger acts on the corresponding target protein molecules
Calcium ions can activate signal transduction-related enzymes
Small molecules such as NO also have a messenger function
enzyme
signal transducer
guanotide binding protein (G or GTP binding protein)
