L3 : Biology of cells

• Signaling molecules : Growth factors • Neurotransmitters • Hormones • Pressure, sound waves
• Cell receptors : 1. G-protein-coupled receptors 2. Ion channel receptors 3. Enzyme-linked receptors
• Cell adhesion and communication

  A) transporter

  B) receptor

  C) enzyme

  D) anchor

  
• Second messengers 1. Cyclic AMP (cAMP) 2. Diacylglycerol (DAG) 3. Inositol 1,4,5-triphosphate (IP3) → Ca2+
• DAG and IP3 are produced by *phospholipase
• DAG and Ca2+ activate protein kinase C
• PKA and PKC activate *protein phosphorylation
• G-protein-coupled receptors

  
• Ion channel receptors

  
• Excitable cells (ถูกกระตุ้นได้ ตอบสนองรวดเร็ว) : Neurons, muscle cells, touch receptor cells • Convert chemical/mechanical signals into *electrical signals • Pressure, sound wave

  Ion channels : Multimeric proteins • Open/close by signals (milliseconds) • Create “electrochemical gradient”
• Receptor Tyrosine Kinase (RTKs)

  Regulate cell growth, differentiation and survival : Growth factors • Hormones • Locally released proteins (cytokines) • Cross- phosphorylation
• Receptor Tyrosine Kinase (RTKs)

  Changes in gene transcription 1. Mitogen-activated protein (MAP) kinase cascade 2. *Phosphoinositide 3-kinase 3. Signal transducers and activators of transcription (STAT proteins)
• Surface protein “ephrins” help guide developmental process of tissue architecture, final placement of nerve ending, and blood vessel maturation
• Collagen synthesis will be discussed during TBL
• 5 junction

  1. Tight junction : Stitch cell together
  2. Adherens junction : Join the actin filaments
  3. Desmosomes : Join the intermediate filaments
  4. Hemidesmosomes : Connect intermediate filaments to the basal lamina
  5. Gap junction : Tunnels between cells
• Gap junction

  • Transmembrane protein “ Connexon”

  • Small molecules and ions can move from one cell to another

  
• adenylyl cyclase : change ATP to cAMP
• Cell motility

  : Cytoskeletal filaments • Microtubules sliding (cilia or flagella move)

  : Actin filament networks (cytokinesis, amoebae movement)
• 1. Microfilaments • Muscle contraction, cytokinesis (actin, microvilli)
  2. Intermediate filaments • Maintain cell structure (vimentin, desmin, cytokeratin, glial fibrillary acid proteins, neurofilaments)
  3. Microtubules • Movement, cell division (cilia, flagella, mitotic spindle, axonal trafficking, centrioles)
• Intracellular sorting 1. Signal sequence 2. Endoplasmic reticulum (ER) 3. Golgi apparatus 4. Lysosome
• Insulin and erythropoietin (EPO) are vesicular proteins
• Integrins โปรตีนที่ฝังตัวใน Plasma mb.
• 1. Signal sequence 2. Endoplasmic reticulum (ER) 3. Golgi apparatus 4. Lysosome

  A) Signal recognition particle (SRP)

  
• exocytosis : ER go to golgi by vesicle.
• endocytosis : endosome + vesicle(Enz. from Golgi) = lysosome(acid condition)