Talk:Pre-Medicine Program - Cell Compartments and Membranes

From CellBiology


Today's class and the class on cell import and export will be self-directed learning exercises.

  1. Work through the content of this online page.
    1. either by yourself or in a group of 2 students with the computer.
  2. Complete a brief quiz on this topic.
    1. in the last 10 minutes a short quiz assessment of your understanding.

Exocytic transport intermediates carrying lipid raft markers



  • Insulin receptor
    • activation induces glucose uptake
    • transmembrane receptor activated by insulin, IGF-I, IGF-II
    • tyrosine kinase receptor.
  • Degradation liver cell endocytosis of the insulin-receptor complex


  • glucagon receptor is a 62 kDa protein that is activated by glucagon
    • G-protein coupled receptor (coupled to G alpha i, Gs and to a lesser extent G alpha q.)
  • mainly expressed in liver and kidney
  • less in heart, adipose tissue, spleen, thymus, adrenal glands, pancreas, cerebral cortex, and gastrointestinal tract.

Historic Papers

Below are some example historical research finding related to cell membranes from the JCB Archive and other sources.

1957 The invention of freeze fracture EM and the determination of membrane structure Russell Steere introduces his home-made contraption for freeze fracture electron microscopy (EM), and Daniel Branton uses it to conclude that membranes are bilayers.

1971 Spectrin is peripheral S. Jonathan Singer, Garth Nicolson, and Vincent Marchesi use red cell ghosts to provide strong evidence for the existence of peripheral membrane proteins.

1992 Lipid raft idea is floated Gerrit van Meer and Kai Simons get the first hints of lipid rafts based on lipid sorting experiments.

Links: Sorted JCB Archive -Membranes JCB Archive



Search Online Textbooks



Vertebrate membrane proteins: structure, function, and insights from biophysical approaches. Müller DJ, Wu N, Palczewski K. Pharmacol Rev. 2008 Mar;60(1):43-78. Epub 2008 Mar 5. Review. PMID: 18321962


Internal Links

External Links



  • A myosin V moves yeast secretory vesicles Secretory vesicles actively move to the site of exocytosis in yeast. Schott et al. find that multiple secretory vesicles often follow the same linear track and frequently enter and cross the bud. This movement requires the activity of the myosin-V heavy chain encoded by the MYO2 gene. When the predicted lever arm of this motor is progressively shortened (with the most extreme example being the 0IQ mutant), the vesicle movements are progressively slowed.
  • Rapid cycling of lipid rafts to and from the Golgi Nichols et al. detect rapid cycling of lipid raft markers between the plasma membrane and the Golgi. Through selective photobleaching, they are able to study transport either out from the Golgi to the plasma membrane, or in from the plasma membrane to the Golgi.
  • Membrane docking at the immunological synapse requires Rab27a Stinchcombe et al. find that normal membrane docking of lytic granules at the immunological synapse is defective in cells lacking Rab27a. In cells lacking other Rab proteins, polarization of the secretory granules is incomplete.
  • Visualizing the location and dynamics of exocytosis Schmoranzer et al. use total internal reflection (TIR) fluorescence microscopy to visualize exocytosis in mammalian cells (e.g., see event on left side of video). The analysis reveals that there are no preferred sites for constitutive exocytosis in this system.
  • Visualizing the location and dynamics of exocytosis Toomre et al. use a combination of TIR microscopy (green, labeling molecules close to or at the membrane) and standard fluorescence microscopy (red, for molecules further from the membrane) to visualize trafficking to and fusion with the plasma membrane during exocytosis. Red dots turn yellow then green as they approach the membrane, and then explode in a burst of light as they fuse with the plasma membrane during exocytosis. The transport containers appear to be partially anchored at the membrane before fusion, and can undergo either partial or complete fusion events.

PLoS Movies

Online Movies