title: Functional evolution of two subtly different (similar) folds.
abstract: BACKGROUND
  The function of proteins is a direct consequence of their three-dimensional structure. The structural classification of proteins describes the ways of folding patterns all proteins could adopt. Although, the protein folds were described in many ways the functional properties of individual folds were not studied.
  
  
  RESULTS
  We have analyzed two beta-barrel folds generally adopted by small proteins to be looking similar but have different topology. On the basis of the topology they could be divided into two different folds named SH3-fold and OB-fold. There was no sequence homology between any of the proteins considered. The sequence diversity and loop variability was found to be important for various binding functions.
  
  
  CONCLUSIONS
  The function of Oligonucleotide/oligosaccharide-binding (OB) fold proteins was restricted to either DNA/RNA binding or sugar binding whereas the Src homology 3 (SH3) domain like proteins bind to a variety of ligands through loop modulations. A question was raised whether the evolution of these two folds was through DNA shuffling.
authors.affiliation: Institute of Microbial Technology, Sector 39-A, Chandigarh 160 036, India. vishal@imtech.res.in
authors.forename: V
authors.initials: V
authors.lastname: Agrawal
authors.forename: R K
authors.initials: RK
authors.lastname: Kishan
mesh_terms: D000595:Amino Acid Sequence; D005075:Biological Evolution; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000235:genetics; D016415:Sequence Alignment; D018909:src Homology Domains
chemical_list: D009841:Oligonucleotides; D009844:Oligosaccharides