The proliferation of research in this area has unfortunately also led to the adoption of many overlapping and contradictory nomenclatures and classifications for the same sets of genes/proteins. Some XET/EXGT genes have been assigned more than one name in the public databases. Now that the genomes of a monocotyledon (Oryza sativa) and a dicotyledon (Arabidopsis thaliana) have been sequenced and the extensive nature of this class of genes has been revealed, this seems an appropriate time to develop a systematic and logical approach to naming new and existing XET/EXGT genes. This will become increasingly important as the databases expand and additional large-scale plant genome sequencing initiatives progress.

A standardized nomenclature is urgently needed. A consensus has been reached that a member of this class of genes/proteins should be termed a xyloglucan endotransglucosylase-hydrolase (XTH) (Rose et al. 2002). This name was selected to accurately describe the range of enzymatic activities encoded by divergent family members, the specificity of the substrate, and the identity of the glycosyl residues (glucose) that are covalently linked during the transglycosylation reaction. The adoption of a three-letter mnemonic also conforms to the convention for naming gene families.

We propose the following:

  1. The XTH nomenclature should be adopted universally when naming newly identified genes that, based on sequence homology, would previously been designated as an XET or EXGT. The availability of the entire genome sequences of rice and Arabidopsis should make the identification of XTH orthologs relatively easy.
  2. Newly identified XTH genes should be named with the first letter of the genus and the species, followed by a hyphen and then the XTH mnemonic and a number; thus we have designated the members of the Arabidopsis thaliana  XTH gene family At-XTH1, At-XTH2, etc.
  3. To facilitate the naming of newly identified XTH genes researchers with newly identified XTH genes are encouraged to contact us when naming the genes to inform us of the new gene name and accession number. Researchers who have already named and published XET/EXGT gene sequences are encouraged also to contact the website to allow a new XTH designation to be assigned.
  4. The two known activities of XTH proteins are referred to enzymologically as xyloglucan endotransglucosylase (XET) activity and xyloglucan endohydrolase (XEH) activity.

CLICK HERE TO SEND US AN E-MAIL REGARDING YOUR XTH GENE/PROTEIN

 

|XTH World Home Page||Rose Lab||Contact us|


s