Question

Can someone explain to me the difference between motif and domain in protein structure. Is a domain just repeated tertiary structural units that are made up of motifs. For example repeated beta-barrels in a protein, that are made up of greek keys?

Answer 1

A domain is usually a functional demarcation in a protein - like DNA-binding domain in a transcription factor for example. A motif is more like a structural designation - so Zinc finger is a motif. I know this is confusing because a DNA binding domain could be made up of zinc fingers, but a DNA - binding domain could also be a helix - turn helix. So I guess the difference is whether you start from crystal structure and define structural motifs or functional data (usually from expressing truncated or mutated proteins) to say which part of a protein does what. Hope that clears it up

Answer 2

They are completely different things it doesn't matter how you interpret the fold of the protein. The prof in my protein structure and function course specifically said they are completely different. Motifs is in between secondary and tertiary structure and domain is in between tertiary and quaternary structure.

Answer 3

I'm still confused by the concept though :\ I'm hoping my interpretation is correct.

Answer 4

But yeah he said there is a general confusing between these two thing so you think he would have illustrated it better in his lecture slides :(

Answer 5

The difference might lie in the self-stabilization of the domains - the bits called domains might form an active configuration on their own or form an active configuration as part of another protein after cloning to make a chimaeric protein. I guess this would make a domain a function of tertiary structure whereas a motif could be spotted from knowledge of secondary structure because motifs are seen in most proteins whereas domains could only be spotted by comparing proteins from the same family. I hope this helps