SMART accession number:SM01208
Description: This domain is found in a wide range of extracellular proteins. It is found tandemly repeated in up to 8 copies. It is found in the N-terminus of peptidases belonging to the M26 family which cleave human IgA. The domain is also found in proteins involved in metabolism of bacterial cell walls suggesting this domain may have an adhesive function.
Interpro abstract (IPR011098):

The G5 domain (named after its conserved glycine residues) is a module of ~80 residues that is found in a variety of enzymes such as Streptococcal IgA peptidases and various glycosyl hydrolases in bacteria. It is found in one to seven copies in association with other domains, such as LysM, bacterial Ig-like, M23 and M26 peptidases, F5/8 type C, vanW or transglycosylase-like. The G5 domain contains a few highly conserved residues. None of these conserved residues are the polar types of amino acids found in active sites, so it seems unlikely this region has an enzymatic function. However, in nearly all cases the G5 domain is associated with a known enzymatic domain. Therefore, the G5 domain may confer localization or substrate specificity on the proteins in which it is found. As a common feature of the proteins containing G5 domains is N-acetylglucosamine binding, it has been suggested that this function might be attributed to the G5 domain. Other alternative functions could be allosteric regulation of the enzymatic domain or cofactor binding [ (PUBMED:15598841) ].

Family alignment:
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There are 18715 G5 domains in 12194 proteins in SMART's nrdb database.

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