understanding protein evolution and the diversity it originates

homologues

share ancestry

paralogues

two different proteins with a common ancestor

orthologues

same protein from 2 different species

analogues

proteins with similar function but from unrelated genes

types of mutations observed when looking at sequence alignments

point mutations, insertions, deletions

what other mechanisms are involved in protein evolution

gene duplications, exon shuffling, alternative mRNA splicing

gene duplication

two copies of the same starting material evolve and accumulate mutations separately, likely produces homologues

example of gene duplication

icosahedral viruses, the whole capsid can be created from multiple copies of just one protein

insect viruses, use three copies of structurally very similar proteins with the same jelly roll domain

exon shuffling

multiple genes recombine, multi-domain proteins may be created which may or may not work together and present an advantrage

example of exon shuffling

diptheria toxin, the most lethal protein - one molecule can kill an entire cell

diptheria toxin structure

all-alpha domain, greek key domain,rare alpha-beta domain all held together with flexible linkers

alternative mRNA splicing

part of a stress response from plants, may give rise to proteins of different length and activity