Three major classes of animal-cell junctions: 

1. Anchoring junctions

2. Tight junctions

3. Gap junctions

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Fat and muscle cells express large amounts of the insulin-responsive glucose transporter GLUT4

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In resting cells, the majority of the GLUT4 protein is

localized to specialized GLUT4 storage vesicles (GSVs)

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GSVs tethered to the Golgi matrix, by a protein termed TUG (Tether containing a UBX domain for GLUT4).

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Binding of insulin to its receptor triggers activation of a protease that catalyzes a site-specific endoproteolytic cleavage of TUG

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Released N-terminal TUG fragment bind to the kinesin, initiates the microtubule-based movement of the GSVs to the plasma membrane.

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Movement of the GSVs to the plasma membrane is regulated by two monomeric GTP-binding proteins -RalA and Rab10