Actin

The final shape (conformation) of a protein is determined by the intramolecular interactions between the amino acid R-groups, hydrophobic interactions and covalent interactions.

In essence, the binding of a ligand alters the forces within the protein. An example could be: If a ligand binds to a certain 'hinge' domain on a protein which 'pulls' it out its natural position and exposes an usually-covered hydrophobic region. This now-exposed hydrophobic region can interact with other hydrophobic regions and cause the protein to change shape.

The binding of charged ligands can also alter the charge of nearby R-groups through electrostatic forces. If a certain R-group that is usually negative becomes positive, it may bind with a downstream negative R-group via an ionic bond. Or, the ligand may alter the charge at one end of the protein - altering its interactions with the opposite end.

I don't think you need to really worry about the detail of how it occurs, because I don't think scientists are completely sure on how it occurs either. Just know that ligand-binding alters the chemistry and bonding within the protein, which in turn alters its shape (conformational change). Whilst the ligand binding alters the chemistry and bonding of a protein, many proteins are "conformationally flexible" - meaning that removal of the ligand will allow the natural bonding to resume and the protein to return to its original shape. This flexibility between different states is what allows proteins to control biochemical pathways (e.g. ON or OFF).

Thanks so much really helped! So in laymans terms when a ligand bond's it can unlock certain 'blockages' in the protein allowing for chain reaction-like changes due to electro diffusion and concentration based diffusion? That sounds awesome