| Symbol: | GCM |
| GCM | |
| Pfam: | PF03615 |
| Pfam Clan: | CL0274 |
| Interpro: | IPR003902 |
| Prosite: | PS50807 |
| Scop: | 1odh |
In molecular biology, the GCM transcription factors are a family of proteins which contain a GCM motif. The GCM motif is a domain that has been identified in proteins belonging to a family of transcriptional regulators involved in fundamental developmental processes which comprise Drosophila melanogaster GCM and its mammalian homologues (human GCM1 and GCM2).[1] [2] [3] [4] In GCM transcription factors the N-terminal moiety contains a DNA-binding domain of 150 amino acids. Sequence conservation is highest in this GCM domain. In contrast, the C-terminal moiety contains one or two transactivating regions and is only poorly conserved.
The GCM motif has been shown to be a DNA binding domain that recognises preferentially the nonpalindromic octamer 5'-ATGCGGGT-3'.[1] [2] [3] The GCM motif contains many conserved basic amino acid residues, seven cysteine residues, and four histidine residues.[1] The conserved cysteines are involved in shaping the overall conformation of the domain, in the process of DNA binding and in the redox regulation of DNA binding.[3] The GCM domain as a new class of Zn-containing DNA-binding domain with no similarity to any other DNA-binding domain.[5] The GCM domain consists of a large and a small domain tethered together by one of the two Zn ions present in the structure. The large and the small domains comprise five- and three-stranded beta-sheets, respectively, with three small helical segments packed against the same side of the two beta-sheets. The GCM domain exercises a novel mode of sequence-specific DNA recognition, where the five-stranded beta-pleated sheet inserts into the major groove of the DNA. Residues protruding from the edge strand of the beta-pleated sheet and the following loop and strand contact the bases and backbone of both DNA strands, providing specificity for its DNA target site.