SNF2 family of proteins.

The SNF2 family of proteins is defined by the presence of a conserved set of amino-acid motifs which together are called the SNF2 domain (for reviews see Bork and Koonin (1993) or Eisen et al., (1995).

This domain is found in proteins involved in a variety of processes including:

• transcription regulation (e.g., MOT1, SNF2 and BRM),
• chromatin unwinding (e.g., ISWI),
• maintenance of chromosome stability during mitosis (e.g. lodestar)
• nucleotide excision repair (e.g. RAD16 and CS-B),
• recombinational pathways (e.g. RAD54)
• post-replication daughter strand gap repair (e.g. RAD5)

All proteins in the SNF2 family contain sequence motifs similar to those found in many DNA and RNA helicase protein families. Proteins with these "helicase" motifs have been divided into multiple superfamilies based upon amino acid sequence patterns found within the motifs. By this method the SNF2 family has been assigned to helicase superfamily 2, which also includes the ERCC3, RAD3, PRIA, EIF4A and PRP16 protein families.

Despite the presence of the "helicase" motifs, no protein in the SNF2 family has yet been shown to have helicase activity. The "helicase" motifs are likely indications of DNA-dependent ATPase activity, of which helicase activity is a subset.

Defects in proteins in this family are the causes of two human hereditary diseases: Cockayne's Syndrome and ATR-X syndrome.

The SNF2 family can be divided into multiple evolutionarily and functionally distinct subfamilies(see Evolution and Subfamilies sections)