This web page was produced as an assignment for Genetics 564, an undergraduate capstone course at UW-Madison.
What is Homology?
Homology is defined as the relationship between different entities such as anatomical structures, proteins, or genes in organisms of different species. Two entities are said to be homologous if they were derived from a common ancestor [1]. An example of homology is depicted in the diagram above, where the structure of the limbs of different animals are derived from the same common ancestor. The limb of each animal varies in form and function but they all share the common components of a limb that their ancestor once had. At the molecular level, the similar concept can be applied and proteins are said to be homologous when they share common sequences between each other [2]. Likewise, the human MEF2C protein has homologs across different species and some of them are listed below. Understanding homology is crucial in research because it enables scientists to study proteins or genes that have similar functions and are related to humans using more efficient systems like model organisms.
MEF2C homologs
Pan Troglydes (Chimpanzee)
MEF2C (Isoform X11 ) Accession number: XP_001142588.1 Length: 483 aa 100% identity |
Macaca mulatta (Rhesus macaque)
MEF2C (isoform X7) Accession number: XP_014995870.1 Length: 483 aa 100% identity |
Rattus norvegicus (Norway rat)
MEF2C (isoform X2) Accession number: XP_017449856.1 Length: 465 aa 92% identity |
Canis lupus familiaris (Dog)
MEF2C (isoform X1) Accession number: XP_005618186.1 Length: 473 aa 91% identity |
Mus musculus (House mouse)
MEF2C (Isoform 1) Accession number: NP_001164008 Length: 466 aa 97% identity Xenopus Tropicalis (Tropical clawed frog)
MEF2C Accession number: NP_001106387.1 Length: 432 aa 82% identity |
Drosophila Melanogaster (Fruit fly)
MEF2 (isoform D) Accession number: NP_477020.1 Length: 540 aa 41% identity |
Gallus gallus (Chicken)
MEF2C (isoform X5) Accession number: XP_015136052.1 Length: 441 aa 84% identity |
Latimeria chalumnae (Coelacanth)
MEF2C (isoform X6) Accession number: XP_014344547.1 Length: 446 aa 84% identity |
Caenorhabditis elegans (Roundworm)
MEF2 related Accession number: NP_492441.1 Length: 340 aa 85% identity |
Arabidopsis thaliana (Thale cress)
AGAMOUS-like 42 Accession number: NP_001330218.1 Length: 107 aa 42% identity |
Discussion
MEF2C is conserved enough that it is found in many types of organisms including plants and yeast. This is because MEF2C is part of the MEF2 family, which belong to the evolutionarily ancient MADS (MCM1, AGAMOUS, DEFICIENS, and SRF)-box superfamily [3]. The percent identity of MEF2C is higher in vertebrates compared to invertebrates because vertebrates have a Holliday junction recognition protein C-terminal (HJURP_C) domain. Hence, the high overall conservation of MEF2C shows that this gene is highly important in the development and function of various organisms.
References:
[1] Berg JM, Tymoczko JL, Stryer L. Biochemistry. 5th edition. New York: W H Freeman; 2002. Section 7.1, Homologs Are Descended from a Common Ancestor.
[2] Koonin, E. V. (2005). Orthologs, paralogs, and evolutionary genomics. Annu. Rev. Genet., 39, 309-338.
[3] Wu, W., de Folter, S., Shen, X., Zhang, W., & Tao, S. (2011). Vertebrate paralogous MEF2 genes: origin, conservation, and evolution. PloS one, 6(3), e17334.
Images:
Fig, 1: https://1.bp.blogspot.com/-iXWSOjDLPlA/V1splSxYeVI/AAAAAAAAT2g/hnKxdwatIKYTFLfkXUWehaOZ1CbYpQVsQCLcB/s1600/forelimb_homology.jpeg
Homolog organism images are hyperlinked to their respective sources.
Header: http://afracturedreality.tumblr.com/post/44787555890/brainbow-zebrafish
[1] Berg JM, Tymoczko JL, Stryer L. Biochemistry. 5th edition. New York: W H Freeman; 2002. Section 7.1, Homologs Are Descended from a Common Ancestor.
[2] Koonin, E. V. (2005). Orthologs, paralogs, and evolutionary genomics. Annu. Rev. Genet., 39, 309-338.
[3] Wu, W., de Folter, S., Shen, X., Zhang, W., & Tao, S. (2011). Vertebrate paralogous MEF2 genes: origin, conservation, and evolution. PloS one, 6(3), e17334.
Images:
Fig, 1: https://1.bp.blogspot.com/-iXWSOjDLPlA/V1splSxYeVI/AAAAAAAAT2g/hnKxdwatIKYTFLfkXUWehaOZ1CbYpQVsQCLcB/s1600/forelimb_homology.jpeg
Homolog organism images are hyperlinked to their respective sources.
Header: http://afracturedreality.tumblr.com/post/44787555890/brainbow-zebrafish