A post-translational modification (PTM) describes a form of biosynthesis for the task of initializing proteins for specific functions. PTMs are complexes which are involved in de- veloping or customizing proteins to increase their functional diversity. In times of protein stress, PTMs may be involved in altering protein structures to allow for better chances of survival. Once the stress-condition has elapsed, PTMs are able to transform the protein's structure back to its original form for the continued survival of the protein. PTMs are not applied uniformly across organismal proteins and dif- fering PTM preferences and usages may often exist between proteins of the same organism. Here, we study the frequency of factors (PTM predominance and their associated active sites, tRNAs and amino acids) which likely in uence a PTM bias. We extract and study these factor frequencies across both mitochondrial (Mt) and non-Mt proteins of nine diverse organisms (closely following two, Arabidopsis thaliana and Caenorhabditis elegans, due to space limitations) to illus- Trate their remarkable differences which may strongly in u- ence natural PTM selection. By this work, weoer evidence to argue that this PTM bias may be the result of these fac- Tors which combine in a poorly understood system to affect and control PTM interactions. Our analysis is made up of an application of frequency information concerning PTMs, active sites, tRNA and amino acids and is used to create network models for the clear visualization of its mechanisms for this PTM natural selection.