Genealogy of the alpha-crystallin--small heat-shock protein superfamily

Int J Biol Macromol. 1998 May-Jun;22(3-4):151-62. doi: 10.1016/s0141-8130(98)00013-0.


Sequences of 40 very diverse representatives of the alpha-crystallin-small heat-shock protein (alpha-Hsp) superfamily are compared. Their characteristic C-terminal 'alpha-crystallin domain' of 80-100 residues contains short consensus sequences that are highly conserved from prokaryotes to eukaryotes. There are, in addition, some positions that clearly distinguish animal from non-animal alpha-Hsps. The alpha-crystallin domain is predicted to consist of two hydrophobic beta-sheet motifs, separated by a hydrophilic region which is variable in length. Combination of a conserved alpha-crystallin domain with a variable N-terminal domain and C-terminal extension probably modulates the properties of the various alpha-Hsps as stress-protective and structural oligomeric proteins. Phylogeny reconstruction indicates that multiple alpha-Hsps were already present in the last common ancestor of pro- and eukaryotes. It is suggested that during eukaryote evolution, animal and non-animal alpha-Hsps originated from different ancestral gene copies. Repeated gene duplications gave rise to the multiple alpha-Hsps present in most organisms.

Publication types

  • Comparative Study
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Conserved Sequence
  • Crystallins / chemistry*
  • Crystallins / genetics*
  • Crystallins / physiology
  • Evolution, Molecular
  • Gene Expression
  • Heat-Shock Proteins / chemistry*
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / physiology
  • Humans
  • Mammals
  • Molecular Sequence Data
  • Multigene Family
  • Phylogeny
  • Protein Structure, Secondary
  • Sequence Homology, Amino Acid
  • Vertebrates


  • Crystallins
  • Heat-Shock Proteins