Protein Families Arise When a Protein Sequence That Generates a Stable

Essay

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 multi-subunit protein.