Question

Protein families arise when a protein sequence that generates a stable fold diverges over many generations and acquires new functions. One example of this can be seen in the globin family. Myoglobin is a stable monomeric protein that can help carry oxygen using a heme molecule. Hemoglobin is stable as a tetramer. It also carries oxygen through the use of heme groups, but it is useful over a much more dynamic range of oxygen than myoglobin. The "globin fold" is structurally conserved across these proteins, but the ability to tetramerize arose through genetic drift and natural selection. Provide an explanation for how the globin sequence can change and still produce the same overall fold. Support your explanation by suggesting the location and type of sequence alterations that might have little effect on the overall protein fold, but may favor the formation of a multisubunit protein.

Answer 1

The globin sequence can change and still produce the same overall fold by having sequence alterations that have little effect on the protein fold but may favor the formation of a multisubunit protein.

Step-by-step explanation:

The globin sequence can change and still produce the same overall fold due to the structural conservation of the globin fold. Changes in the primary sequence can occur at certain locations and types of sequence alterations that have little effect on the overall protein fold but may favor the formation of a multisubunit protein.

For example, amino acid substitutions that maintain the overall charge or size of a residue may have minimal impact on the protein fold. Additionally, alterations in loops or surface residues that do not directly interact with the core fold can be tolerated without affecting the protein structure.