How does Bt toxin work?

I would like to know a clear process of how BT toxin works to kill insects. Many websites say different things and are not really clear.

I will post two of the processes from two different websites.

Process 1:

1. Insect eats Bt crystals and spores.

2. The toxin binds to specific receptors in the gut and the insects stops eating.

3. The crystals cause the gut wall to break down, allowing spores and normal gut bacteria to enter the body.

4. The insect dies as spores and gut bacteria proliferate in the body.

Process 2:

Unlike typical nerve-poison insecticides, Bt acts by producing proteins (delta-endotoxin, the "toxic crystal") that reacts with the cells of the gut lining of susceptible insects. These Bt proteins paralyze the digestive system, and the infected insect stops feeding within hours. Bt-affected insects generally die from starvation, which can take several days.

Occasionally, the bacteria enter the insect's blood and reproduce within the insect. However, in most insects it is the reaction of the protein crystal that is lethal to the insect. Even dead bacteria containing the proteins are effective insecticides.

I have pasted the two processes from the website links below.

Process 1 website link - http://www.bt.ucsd.edu/how_bt_work.html

Process 2 website link - http://www.ext.colostate.edu/pubs/insect/05556.html

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