Protein subfamily is a level of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

classification, based on their close evolutionary relationship. It is below the larger levels of

protein superfamily A protein superfamily is the largest grouping (clade) of proteins for which common ancestry can be inferred (see homology (biology), homology). Usually this common ancestry is inferred from structural alignment and mechanistic similarity, even if n ...

and

protein family A protein family is a group of evolutionarily related proteins. In many cases, a protein family has a corresponding gene family, in which each gene encodes a corresponding protein with a 1:1 relationship. The term "protein family" should not be c ...

. Proteins typically share greater sequence and function similarities with other subfamily members than they do with members of their wider family. For example, in the

Structural Classification of Proteins The Structural Classification of Proteins (SCOP) database is a largely manual classification of protein structural domains based on similarities of their structures and amino acid sequences. A motivation for this classification is to determine t ...

database classification system, members of a subfamily share the same interaction interfaces and interaction partners. These are stricter criteria than for a family, where members have similar structures, but may be more distantly related and so have different interfaces. Subfamilies are assigned by a variety of methods, including

sequence similarity Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a spec ...

, motifs linked to function, or

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

clade. There is no exact and consistent distinction between a subfamily and a family. The same group of proteins may sometimes be described as a family or a subfamily, depending on the context.

References

External links

SCOP DB at Cambridge UK

CATH protein structure DB
Protein classification {{protein-stub