Primary Structure (amino acid sequence)
Secondary Structure (alpha helix and beta sheet)
Tertiary Structure (overall 3-D structure)
Motifs are conserved primary sequences or simple combinations of a few secondary structural elements.
Glycosylation sites, phosphorylation sites, ATP binding site
Domains are fundamental units of tertiary structure.
These are polypeptide chains that can fold independently into a stable tertiary structure.
They can also form units of function.
Domains are built from structural motifs.
Transcription Factors (TF) - bind to DNA and turn genes on or off.
DNA binding domains (H-T-H)
Dimerization domains (alpha helix)
By swapping domains a proteins activity can be changed
New proteins are made by exchange of domains and by mutations within domains
Add additional domains or make mutations to change members of the same family.
Glucocorticoid receptors - similar structure with different DNA binding and hormone binding domains
Look at DNA binding motif in steroid receptors
Compare Urokinase, Factor IX and Plasminogen