Harvard University and XVIVO have come together again (Previouslyw/ a commercial focus, Previouslierw/an Academic focus) to add to the growing series of scientific animations for BioVisions -- Harvard's multimedia lab in the department of Molecular and Cellular Biology. 'Protein Packing' strives to more accurately depict the molecular chaos in each and every cell, with proteins jittering around in what may seem like random motion. Proteins occupy roughly 40% of the cytoplasm, creating an environment that risks unintentional interaction and aggregation. Via diffusion and motor protein transport, these molecules are directed to sites where they are needed.
Much of this is no doubt inspired by the beautiful art and explained illustrations of David Goodsell, a biologist at Scripps who has been accurately portraying the crowdedness of the cellular landscape for a long time now.[more inside]
Constitutive formation of caveolae in a bacterium. [Full Text]
Caveolin plays an essential role in the formation of characteristic surface pits, caveolae, which cover the surface of many animal cells. The fundamental principles of caveola formation are only slowly emerging. Here we show that caveolin expression in a prokaryotic host lacking any intracellular membrane system drives the formation of cytoplasmic vesicles containing polymeric caveolin. Vesicle formation is induced by expression of wild-type caveolins, but not caveolin mutants defective in caveola formation in mammalian systems. In addition, cryoelectron tomography shows that the induced membrane domains are equivalent in size and caveolin density to native caveolae and reveals a possible polyhedral arrangement of caveolin oligomers. The caveolin-induced vesicles or heterologous caveolae (h-caveolae) form by budding in from the cytoplasmic membrane, generating a membrane domain with distinct lipid composition. Periplasmic solutes are encapsulated in the budding h-caveola, and purified h-caveolae can be tailored to be targeted to specific cells of interest.Elio Schaechter writes in plain English about how fantastically amazing and unexpected the researchers actually pulling this off is, and he also talks about it in more detail in his podcast.