Riboflavin is indispensable for cellular metabolism because it is the precursor of coenzymes flavin mononucleotide (FMN) and flavin adenie dinucleotide (FAD) (LeBlanc et al. 2011; Aller et al. 2014).
The non-protein-coding regions of the mtDNA are indispensable for cellular energy homeostasis, and genetic variation in these regions could have metabolic and fitness consequences.
By binding downstream effectors like regulator for cell adhesion and polarization enriched in lymphoid tissues (RAPL) and Rap1-GTP-interacting adaptor molecule (RIAM), Rap1 connects to talin [12] and induces lymphocyte polarization by distributing LFA-1 to the leading edge, which is indispensable for cellular adhesion and migration [13], [14].
PDFs are essential enzymes and their activities are indispensable for cellular function [ 92, 94].
The lysosomal compartment is indispensable for cellular life and has several important functions.
Other studies have shown that HNRNPK is a functional constituent of a cellular structure, the spreading initiation centre, and that it is indispensable for cellular migration.
Essential genes encode proteins that are indispensable for cellular growth; hence such genes can be viewed as having "extreme control" on growth.
Nevertheless, the activity of the protein is indispensable for cellular proliferation, and a reduction of its activity in tumors results in growth inhibition [109,110].
Moreover, considering the signaling role of phosphorylation, which is indispensable for cellular structure, neuroplasticity and communication, the protein candidates presented here be considered therapeutic targets to be further explored in drug response and drug discovery studies.
On the basis of the data that targeted deletion of the BRCT domain results in embryonic lethality (Hohenstein et al, 2001), BRCT is postulated to be indispensable for the normal cellular growth, and it would be intriguing to investigate physiological functions of BRCT.
