What are protein domains?
Domains are conserved functional or structural units of proteins. They are independently stable, which means they retains their structure and function when cleaved off from the rest of the protein. Protein motifs are small regions of protein structure that are not stable independently [1]. Identifying domains and motifs in proteins allows for classification of proteins and identifying possible functions of unknown proteins, which can impact genetic research and the understanding of diseases in medicine [2]. Programs such as SMART and Pfam can be used to provide identification and annotation of protein domains through visualization tools.
Domains of SGSH and their functions
Sulfatases are enzymes that hydrolyze various sulphate esters. This domain is involved in the metabolic process. N-sulfoglucosamine sulfohydrolase (SGSH) is a specific type of sulfatase and a lysosomal enzyme which catalyzes the hydrolysis of N-sulpho-d-glucosamine into glucosamine and sulphate.
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Domain of unknown function (DUF4976) are domains with no specific information about their functions. DUF consists of uncharacterized proteins around 530 residues and is mainly found in bacteria. Interestingly, almost all of the domain organizations in which this domain is found in also contain the sulfatase domain.
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Conserved domains in SGSH
The following figure shows the conserved domains, sulfatase and DUF4976, mapped into amino acid sequences among the model organisms drosophila, zebrafish, mouse, and rat. Zebrafish only contains the sulfatase domain.
Discussion
SGSH was found to have two conserved domains among species. All models except zebrafish had the same two domains, sulfatase and DUF4976. The conservation of domains among species suggests their key role in the function of protein and in Sanfilippo syndrome. The results can also help us choose a proper model organism that shares the conserved domains.
References
[1] https://www.ebi.ac.uk/training/online/course/introduction-protein-classification-ebi/protein-classification/what-are-protein-domains
[2] https://www.ncbi.nlm.nih.gov/pubmed/27896721
Header: https://en.wikipedia.org/wiki/Protein_domain#/media/File:Pyruvate_kinase_protein_domains.png
[2] https://www.ncbi.nlm.nih.gov/pubmed/27896721
Header: https://en.wikipedia.org/wiki/Protein_domain#/media/File:Pyruvate_kinase_protein_domains.png
This web page was produced as an assignment for Genetics 564, an undergraduate capstone course at UW-Madison.