ቤተ መጻሕፍቲ ባይዱ
1. Extracellular signal molecules: Ligand/Agonist are normally released by signal-producing cells, reach and bind to the receptor protein of target cells.
Distribution:
• Cell surface receptors • Intracellular receptors
Domains of cell surface receptors:
• The extracellular segment---binding site
• The hydrophobic membrane spanning segment--- Transmembrane （ highly conserved）
Fatty acid derivatives:
Prostaglandins
Extracellular molecules
Bind to
intracellular-- Steroid hormones,
receptors
Thyroxine , VD3
Physical Signal
light, wave, voice, pressure & temperature
Signal molecules
Ligand/Agonist
Proteins and peptides:
Hormones, cytokines
Bind to Amino acid derivatives: membrane Catecholamine receptors
Chemical Signal
effector. Transducers could be enzymes, adaptor, or others. Transduction is a multi-step process.
4. Effector proteins – produces a 2nd messenger such as cAMP.
2. Receptor proteins –are specific proteins, which are able to recognize and bind to corresponding ligands, and transduce signal to next signaling molecules inside of the cell.
• The cytoplasmic segment---enzyme domain（ highly conserved），transferring a phosphate group from ATP to tyrosine or serine/threonine on a substrate protein.
CONTENT
1. Overview: Concept, components, common features of cell signal transduction pathways
2. Ras-Raf-MAPK pathway 3. PI3K/AKT/mTOR pathway 4. Jak-STAT pathway 5. NF-kB pathway 6. Notch pathway 7. Abnormal Cell signaling and diseases
Types of signal molecules— Lipid-soluble molecules Water-soluble molecules Gaseous molecules (NO)
Properties of signal molecules— Specificity, highly efficient, competitive Dosage-dependent, saturable Reversible, can be deactivated
OVERVIEW
Definition
Signal transduction refers to the process that the extracellular stimuli regulate the biological functions, through membranous or intracellular receptors mediated signal cascade.
Schematic view of Cell signaling
Growth factors
Signals Cytokines Extracellular matrix proteins
Cell stresses
Biochemical processes
Proliferation Differentiation
1. act as cell’s ‘letter boxes’, and receive messages
2. Transmit a message into the cell, which normally leads to a specific cellular effect
3. Each cell has multiple specific receptors, making it responsive to different chemicals.
Motility
Death Transformation
Cell signaling affects virtually EVERY ASPECT of cell structures and functions.
COMPONENTS
1. Extracellular signal molecules: Ligand/Agonist. 2. Receptor –are specific proteins, which are able to recognize and bind to corresponding ligands. Binding is specific, but not always in 1-1 fashion. 3. Transducers – carries the message from the receptor to the