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605  structures 9463  species 23  interactions 45797  sequences 260  architectures

Clan: GCS (CL0286)


gamma-glutamylcysteine synthetase/glutamine synthetase clan Add an annotation

This clan represents a superfamily of carboxylate-amine/ammonia ligases [1] that includes Gamma-Glutamylcysteine synthetase (gamma-GCS) and glutamine synthetase (GS). Gamma-Glutamylcysteine synthetase (gamma-GCS) catalyses the first step in the de novo biosynthesis of glutathione.

This clan contains 9 families and the total number of domains in the clan is 45797. The clan was built by A Bateman and J Pei.

Literature references

  1. Abbott JJ, Pei J, Ford JL, Qi Y, Grishin VN, Pitcher LA, Phillips MA, Grishin NV; , J Biol Chem. 2001;276:42099-42107.: Structure prediction and active site analysis of the metal binding determinants in gamma -glutamylcysteine synthetase. PUBMED:11527962 EPMC:11527962


This clan contains the following 9 member families:

Amidoligase_2 ATP-gua_Ptrans DUF2126 GatB_N GCS GCS2 Gln-synt_C Glu_cys_ligase Pup_ligase

External database links

Domain organisation

Below is a listing of the unique domain organisations or architectures from this clan. More...

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The table below shows the number of occurrences of each domain throughout the sequence database. More...

Pfam family Num. domains Alignment
Gln-synt_C (PF00120) 20560 (44.9%) View
GatB_N (PF02934) 8664 (18.9%) View
GCS2 (PF04107) 6002 (13.1%) View
ATP-gua_Ptrans (PF00217) 2509 (5.5%) View
Pup_ligase (PF03136) 2152 (4.7%) View
Glu_cys_ligase (PF04262) 1946 (4.2%) View
Amidoligase_2 (PF12224) 1382 (3.0%) View
GCS (PF03074) 1344 (2.9%) View
DUF2126 (PF09899) 1238 (2.7%) View
Total: 9 Total: 45797 Clan alignment

Please note: Clan alignments can be very large and can cause problems for some browsers. Read the note above before viewing.

Family relationships

This diagram shows the relationships between members of this clan. More...

Species distribution

Tree controls


This tree shows the occurrence of the domains in this clan across different species. More...



There are 23 interactions for this clan. More...

Interacting families
Amidase GatB_N
Asparaginase GatB_N
ATP-grasp_4 Glu_cys_ligase
ATP-gua_Ptrans ATP-gua_Ptrans
ATP-gua_PtransN ATP-gua_Ptrans
GatB_N Amidase
Gln-synt_C Gln-synt_C
Gln-synt_N Gln-synt_C
Glu-tRNAGln GatB_N
Glu_cys_ligase ATP-grasp_4
GSIII_N Gln-synt_C
Pup_ligase Pup
tRNA-synt_2 GatB_N


For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the MSD group, to allow us to map Pfam domains onto UniProt three-dimensional structures. The table below shows the mapping between the Pfam families in this clan, the corresponding UniProt entries, and the region of the three-dimensional structures that are available for that sequence.

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