What are domains?
Domains are defined as independent folding units of a protein and can be highly conserved throughout organisms. In the case of 14-3-3sigma, there is one single domain and it is highly conserved in the size and length throughout all of the organisms that I have used in the phylogeny portion of this site as well. Below is an example of what seven of the organisms have as domains [1].
What is the 14-3-3 domain and what does it do?14-3-3 in humans is a 241 amino acid long domain. It is also very well conserved across many organisms and it functions in mediation of signal transduction by binding to phosphoserine-containing proteins. They are involved in growth factor signalling and also interact with MEK kinases [1].
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Figure 1: 14-3-3sigma protein (Human) described by SMART. It shows one ver large 14-3-3 domain. There is only one domain and it is 14 amino acids short of the entire protein.
Figure 2: 14-3-3sigma protein (Human) described by Pfam. It shows a with the very large 14-3-3 domain. There is only one domain and it is 14 amino acids short of the entire protein.
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How well conserved is the protein
and domain across organisms?
It's very clear that this protein is well conserved across these organisms and the domain is highly conserved. It is more conserved across vertebrates, but it is also highly conserved among invertebrates and plants as well.
wHAT ARE mOTIFS?
Motifs are short, conserved regions of the protein that allow the domain to carry out a necessary function. They also described the potential secondary structure of the protein. They are also generally the most highly conserved parts of the genome [2].
Figure 1: 14-3-3sigma Protein Motif 1: Begins at amino acid residue 21 and ends at 70 and repeats at 175 and 224.
Figure 1: 14-3-3sigma Protein Motif 2: Begins at amino acid residue 71 and ends at 120 and repeats at 123 and 172.
Discussion
The idea that the entire protein is just one large exon and one domain demonstrates why this protein is so important and why various crucial cellular processes can not function when this protein is not functioning. The domain also functions by binding to the phospho-serine residues of other proteins leads to my hypothesis that something occurs in these protein interactions that affect cell division. The motifs came at no surprise either because this protein is a dimer, which two helical end portions (amino acid residues 21-70 and 175-224) and a middle section (amino acids 71-172) that is used for binding. This also makes sense that these are the highly conserved regions because the non-conserved regions between organisms generally occurs in the C-terminus and N-terminus.
References
[1] Protein domains and motifs - Pamela Stanley lab wiki. (n.d.). Retrieved May 18, 2015, from http://stanxterm.aecom.yu.edu/wiki/index.php?page=Protein_domains_and_motifs
[2] Timothy L. Bailey and Charles Elkan, "Fitting a mixture model by expectation maximization to discover motifs in biopolymers", Proceedings of the Second International Conference on Intelligent Systems for Molecular Biology, pp. 28-36, AAAI Press, Menlo Park, California, 1994.
[1] Protein domains and motifs - Pamela Stanley lab wiki. (n.d.). Retrieved May 18, 2015, from http://stanxterm.aecom.yu.edu/wiki/index.php?page=Protein_domains_and_motifs
[2] Timothy L. Bailey and Charles Elkan, "Fitting a mixture model by expectation maximization to discover motifs in biopolymers", Proceedings of the Second International Conference on Intelligent Systems for Molecular Biology, pp. 28-36, AAAI Press, Menlo Park, California, 1994.