Question

T/F   Which of the following are true?

_     All proteins with the same (highly similar) 3D structure will have the same function.

_     All proteins with the same function will have the same (highly similar) 3D structure.

_     Functional homologs may share structure, catalytic, and ligand binding sites.

_           Functional homologs may not share sequence similarity

Answer 1

- A protein’s 3D structure largely determines its functional properties. As a result, knowledge of the 3D structure of a protein can yield useful information about the functional properties of the protein. In particular, structural similarity between proteins is a very good predictor of functional similarity. Since a protein’s amino acid sequence determines 3D structure, which in turn determines protein function, one might think that sequence similarity is also very good predictor of functional similarity, but this turns out to be less the case than with structural similarity. Vastly different amino acid sequences can yield very different structures, and similar sequences can sometimes yield dissimilar structures. Thus, sequence similarity is a far less reliable predictor of functional similarity than structural similarity is.

So. All proteins with the same (highly similar) 3D structure will have the same function is false.

All proteins with the same function will have the same (highly similar) 3D structure is true.

the K clusters in NifBMa and NifBMt can be converted to L clusters upon addition of SAM, which corresponds to their ability to heterologously donate L clusters to the biosynthetic machinery of A. vinelandii for further maturation into the M clusters. Perhaps even more excitingly, NifBMa and NifBMt can catalyze the removal of methyl group from SAM and the abstraction of hydrogen from this methyl group by 5?-deoxyadenosyl radical that initiates the radical-based incorporation of methyl-derived carbide into the M cluster.

So, Functional homologs may share structure, catalytic, and ligand binding sites is true.

Functional homologs may not share sequence similarity is true.