Protein Families and Superfamilies

Protein families are groups of homologous proteins with similar amino acid sequences and three-dimensional shapes. They often appear after gene duplication, when an extra copy of a gene is added to an organism’s genome. Mutations can then change the amino acids, as long as the protein can still be made correctly.

A protein family is a group of proteins that have evolved from a common genetic ancestor.  These proteins have similarities in their three-dimensional structures and the functions they perform.  

Proteins within a family are called homologs.  

Orthologs are homologous proteins in different species that evolved from the same protein...