Just use the equivalent functions.
An implicit assumption in the classification of snoRNAs into families is that each family contains members that perform the equivalent biological function across species.
Thus, a requirement on Bub1 for kinetochore recruitment of Mad3/BubR1 is unexpected and suggests that when bound to Mad3/BubR1, Bub3 might be unable to perform an equivalent function in kinetochore recruitment to the one it performs when bound to Bub1.
Orthologs (functional homologs), as a whole, perform an equivalent function in respective genomes [ 23- 25].
Products of the large helicase genes may act in concert with the single-stranded DNA-binding proteins to perform an equivalent function to that of TraI, which is bifunctional, possessing relaxase activity and catalysing a processive 5′- to 3-′ helicase reaction that provides the motive force for strand transfer.
The OC holds that orthologous genes perform equivalent functions in the respective organisms and accordingly, experimentally determined functions of a gene can be transferred to its experimentally uncharacterized orthologs in other species (certainly, taking into account the biological differences between the organisms involved) (Koonin 2005; Gabaldon and Koonin 2013).
Orthologs are defined as genes derived from a single ancestral gene in the last common ancestor of the compared species [ 16] and normally they perform equivalent functions in all species.
For the purposes of this study, we use "homolog" as an umbrella term that encompasses orthologs (genes derived from speciation and that typically perform equivalent functions) and paralogs (genes related by duplication and that generally perform biologically distinct yet mechanistically related functions) (reviewed in Koonin 2005).
Because of this, they are likely to perform equivalent functions, and even if they have diverged since the speciation event, they are more likely to be functional counterparts in different species than other types of homologs (Gabaldón and Koonin, 2013).
Orthologues are separated only by speciation events and represent the direct descendants of a gene in a common ancestor, and therefore usually perform equivalent functions in different species.
