Protein HomologyWhat is Protein Homology?In general, homology between species is an evolutionary similarity that has persisted between species since the divergence from a common ancestor. In terms of proteins, sequence homology is characterized by percent identity, which is the extent to which each amino acid within the sequence is identical across the different species. By identifying homologous proteins between species, we can begin to understand their evolutionary history and identify model organisms to experimentally work with the protein to understand its function and its role in disease.
Identifying FANCL Protein HomologsTo identify homologs of the human FANCL protein, a two-step technique was used to identify and confirm sequence homology. Initially, HomoloGene, a homolog identifier in the NCBI suite of databases, was used to identify the suspected homologs of the FANCL protein [1]. From the resulting output, protein sequences were ran through a reciprocal BLAST to verify the percent identity and confirm their classification as homologous proteins [2].
Homologous Protein References
Analysis of ResultsUtilizing ten species that provided homologous genes with sequence identities above 70%, the identification of homologous proteins provided a slightly different picture of the FANCL gene product. Of particular interest is the Macaca mullata gene homolog which is almost one hundred amino acids longer than all of the other FANCL homologs. This reason for this difference seems to be a single base pair deletion upstream of the FANCL gene, which is analysed under protein phylogeny.
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References
[1] Entrez Help [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2005-. Entrez Help. 2006 Jan 20 [Updated 2014 Apr 9].Available from: http://www.ncbi.nlm.nih.gov/books/NBK3837/
[2] Madden T. The BLAST Sequence Analysis Tool. 2002 Oct 9 [Updated 2003 Aug 13]. In: McEntyre J, Ostell J, editors. The NCBI Handbook [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2002-. Chapter 16. Available from: http://www.ncbi.nlm.nih.gov/books/NBK21097/
[2] Madden T. The BLAST Sequence Analysis Tool. 2002 Oct 9 [Updated 2003 Aug 13]. In: McEntyre J, Ostell J, editors. The NCBI Handbook [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2002-. Chapter 16. Available from: http://www.ncbi.nlm.nih.gov/books/NBK21097/