Bioactive substances secreted by C and capable of regulating body functions are an important class of chemical signaling molecules. By specifically binding to receptors on the C membrane or intracellular, the signal is converted and transmitted to the corresponding intracellular system, allowing Cells respond appropriately to the outside world

1. Hormones: synthesized from endocrine C, reach target cells through blood or lymph circulation, have long-range action, large range, and long time

2.N transmitter: synthesized from N yuan C, reaches the next NC through the synaptic cleft, and has a short action distance and time.

3. Local chemical mediator: synthesized from certain C, does not enter the blood, acts on nearby target cells mediated through extracellular fluid, and has a short action time

1. Definition: A special protein that exists in the cell membrane or within the cell, specifically binds to a ligand, and then activates a series of intracellular biochemical reactions.

2. Characteristics of the interaction between receptor and ligand: specificity, saturability, high affinity, reversibility, and can be regulated by phosphorylation and dephosphorylation

3.Type

4.Second messenger

1.Features

2. MAPK signal transduction pathway: regulates gene expression and participates in the regulation of important physiological processes such as C growth, proliferation, differentiation, and apoptosis.

3. JAK-STAT signal transduction pathway: non-receptor tyrosine kinase, factor C signaling, involved in cell proliferation, differentiation, apoptosis, and immune regulation

4. Wnt signal transduction pathway: improves the stability of β-catenin protein in the cytoplasm and regulates C proliferation, differentiation, and organ development.

5. TGF-β signal transduction pathway: Transforming growth factor-β transduces extracellular signals into the nucleus through the intracellular signaling molecule Smad, regulating C growth, proliferation, differentiation, and organ development.

6. NF-kB signal transduction pathway: nuclear transcription factor, specifically binds to the promoters and enhancer sequences of various genes, regulates gene transcription and expression, and participates in immunity, inflammation, stress response, etc.

1. Signal transduction abnormalities and diseases

2. Signal transduction drug development

3. Tumor