6.1 The inner life of the cell explanation

 http://biologyofcells.blogspot.com/2007/12/cell-membranes.html#lipid-raft

http://evo-sci-glossary.blogspot.com/2005/10/cell-biology-animations.html

The animation opens with the rolling adhesion of a leukocyte within a blood vessel. The surfaces of two cells are shown adhering at contact points between adhesion molecules (selectin-saccharide).

We enter the cell and see a lipid raft, with its embedded proteins, floating within the plasma membrane. Next we see a multi-protein focal contact, and then the cytoskeleton. After glancing back at the sub-plasma membrane 'geodesic' microfilaments, we pass down throught the cytoskeletal lattice and see actin microfilaments assembling, then depolymerizing after attachment of a protein (gelsolin).

Next we see assembly and disassembly of tubulin. This interesting sequence is followed by my favorite segment, which is kinesin dragging an endosomal vesicle along a microtubule as kinesin-bigfoot 'walks' along the tubulin that is radiating from a centriole pair. A fellow kinesin, in the background, actively transports an endosome in the opposite direction.

Next, we approach the nuclear envelope with its embedded nuclear pore complexes. Several mRNA molecules with attached proteins exit the nucleus through the pores and assemble into loops within the cytoplasm, where the mRNA is scanned for a start codon, and is then translated into new polypeptide/protein chains by a ribosome. Globular proteins dimerize and tumble toward a mitochondrion.

Further translation injects a nascent protein chain through a pore into the endoplasmic reticulum as 'bigfoot' continues to clomp along tubulin, dragging a vesicle behind. Next, we see the Golgi apparatus budding vesicles before our plodding kinesin reaches the plasma membrane and proteins are released into the ECF by exocytosis. The newly synthesized integrins float on a lipid raft before unfolding into their active conformation, whereupon they snare a passing leukocyte and induce extravasation.

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