Estrogen Binding

Here can be seen the entire ER from the human genome. The estrogen molecules , shown here in closeup, binds in a highly hydrophobic region surrounded by alpha helices with hydrophobic sidechains exposed to the highly hydrophobic steroid molecule. Phe404, in particular, has a large contribution to the hydrophobic interactions, despite originating from a beta sheet(colored yellow) and not an alpha helix. Along with these, a large contribution is made from the Glu353 , which hydrogen bonds with the 3-hydroxyl group of estrogen, and is held there by hydrogen bonding to Arg394 through a water molecule. His524 is the molecule hydrogen bonding to the other hydroxyl group of the estrogen, thus completing the binding pocket for estrogen .

An alternative picture of the binding pocket can be seen below.

The pictures relating to PR and progesterone are from another study relating the progesterone receptor and the ER.

The binding pocket of estrogen can be seen as highly hydrophobic, with the residues of Glu353 and His524 containing some of the sole polar residues in the area.

The binding of estrogen allows monomers of the ER to homodimerize, and allows the 2 DNA-binding domains to cooperatively bind to the DNA.

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ER binding to the ERE

Zinc-binding Motif

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