I am trying to find some proteins that are non-homologous but functionally similar. However, I cannot seem to find concrete examples. Can someone please point out any resources or provide examples?

  • $\begingroup$ Would something as broad as a gene involved in the development of wings in insects and one involved in the development of wings in birds be a satisfying answer? $\endgroup$ – Remi.b Oct 3 '17 at 16:48
  • $\begingroup$ Yea, sure, that would work. $\endgroup$ – nafizh Oct 3 '17 at 16:51
  • $\begingroup$ By, homologous gene, do you mean gene with independent origin and similar function or independent origin and similar sequence? $\endgroup$ – Remi.b Oct 3 '17 at 17:34
  • $\begingroup$ I mean examples of sequences that are not similar(i.e. you cannot find them by BLASTing) but their functions are similar. $\endgroup$ – nafizh Oct 3 '17 at 17:36

Serine Protease Catalytic Triad

This is classic example of convergent evolution in catalytic mechanisms. Shown below are chymotrypsin (4CHA, green) and subtilisin (1ST2, blue) aligned on their catalytic triads (Ser/His/Asp, darker colours). There is no obvious sequence or structural similarity.

enter image description here

You can check out the MEROPS database for a list of protease clans ("represents one or more families that show evidence of their evolutionary relationship") and this paper for a discussion on convergent evolution of the catalytic triad:

Although the biophysics of rate acceleration are intricate and sensitive to even minor structural perturbations, evolution has converged on a catalytic triad (or diad) with a reactive Ser, Cys, or Thr nucleophile more than 25 separate times to facilitate central biochemical reactions such as hydrolysis, transacylation, and phosphorylation.

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Hoxd12 and Hoxd13 are involved in the development of wings in birds (Vargas and Fallon 2004).

pdm and aptorus are involved in the development of wings in insects (Williams et al. 1993, Averof and Cohen 1997)

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  • $\begingroup$ Thanks. But, which of them are non-homologous? $\endgroup$ – nafizh Oct 3 '17 at 17:19
  • $\begingroup$ Hoxd12 and Hoxd13 are of independent origin than pdm or aptorus but all are involved in the development of wings. $\endgroup$ – Remi.b Oct 3 '17 at 17:33

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