InterPro : IPR003083

Name  S-crystallin Short Name  S-crystallin
Type  Family Description  S-crystallins of cephalopod are the major protein constituent of the lens in cephalopods. Their primary protein sequences show a high degree (41%) of identity with the cephalopod digestive gland sigma-class glutathione transferase (GST). In spite of the sequence similarity, lens S-crystallin shows little if any GST activity. S-crystallins fail to bind to an S-hexylglutathione affinitycolumn (marker for glutathione affinity) and have very little GST activity in a typical substitution reaction with glutathione and 1-chloro-2,4-dinitrobenzene []. Nevertheless, pH rate profiles indicate that anyreactions that do take place proceed via the same mechanism as GSTs []. Sequence analysis suggests that the S-crystallins arose from gene duplication of a cephalopod sigma-class GST [].The three-dimensional structure of the sigma-class GST from squid has beendetermined to 2.4A resolution []. The protein is characterised by two domains, one of which has a 3-layer(aba) sandwich architecture, the otherbeing largely helical. The modelled S-crystallin structure has a similar topology to the squid sigma-class GST, with longer helices 4 and 5, corresponding to a long insertion. The insertion causes the active centreto be in a more closed conformation than sigma-class GSTs and may explainthe low affinity for glutathione [].The function of glutathione S-transferases (GST) is the conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. The isoenzymes appear to play a central role in the parasite detoxification system. Glutathione S-transferases form homodimers, but in eukaryotes can also form heterodimers of the A1 and A2 or YC1 and YC2 subunits. The GST domain is also found in S-crystallins from squid, and proteins with no known GST activity, such as eukaryotic elongation factors 1-gamma and the HSP26 family of stress-related proteins, which include auxin-regulated proteins in plants and stringent starvation proteins in Escherichia coli.

Sequence Features

GO Displayer


InterPro protein domain ID --> Contigs



0 Child Features

4 Contains

Id Name Short Name Type
IPR012336 Thioredoxin-like fold Thioredoxin-like_fold Domain
IPR010987 Glutathione S-transferase, C-terminal-like Glutathione-S-Trfase_C-like Domain
IPR004046 Glutathione S-transferase, C-terminal GST_C Domain
IPR004045 Glutathione S-transferase, N-terminal Glutathione_S-Trfase_N Domain

0 Found In

0 Parent Features

4 Publications

First Author Title Year Journal Volume Pages
Ji X Three-dimensional structure, catalytic properties, and evolution of a sigma class glutathione transferase from squid, a progenitor of the lens S-crystallins of cephalopods. 1995 Biochemistry 34 5317-28
Tang SS Kinetic characterization of the endogenous glutathione transferase activity of octopus lens S-crystallin. 1996 J Biochem 119 1182-8
Chuang CC Homology modeling of cephalopod lens S-crystallin: a natural mutant of sigma-class glutathione transferase with diminished endogenous activity. 1999 Biophys J 76 679-90
Tomarev SI Squid glutathione S-transferase. Relationships with other glutathione S-transferases and S-crystallins of cephalopods. 1993 J Biol Chem 268 4534-42

To cite PlanMine, please refer to the following publication:

Rozanski, A., Moon, H., Brandl, H., Martín-Durán, J. M., Grohme, M., Hüttner, K., Bartscherer, K., Henry, I., & Rink, J. C.
PlanMine 3.0—improvements to a mineable resource of flatworm biology and biodiversity
Nucleic Acids Research, gky1070. doi:10.1093/nar/gky1070 (2018)