Such positive and negative regulations are largely governed by posttranslational modifications on specific amino acid residues on histones (Fig. 1).
In budding yeast, which lacks Pot1 and instead utilises Cdc13 as the main overhang-binding activity, it has been suggested that Stn1/Ten1 compete with Est1 for interaction with Cdc13 and that the outcome of this competition is governed by independent modifications of Cdc13, with phosphorylation by CDK favouring Est1 binding, and SUMOylation instead promoting Stn1/Ten1 association 21.
Such positional memory might be governed by epigenetic modification of homeobox containing or HOX-genes that have been shown to be important for patterning the primary and secondary axes [24], [25].
Epigenetic regulation governed by arginine modification is an emerging hallmark of eukaryotic organisms, and interference with the underlying enzymes holds great promise to intervene in various diseases ranging from cancer to rheumatoid arthritis.
Promoter elements governed by specific epigenetic modifications that can shift from an 'active' accessible state to a 'repressed' state and vice versa.
Loss of pluripotency seems to be accompanied with limitation of replicative live span and this might be governed by specific epigenetic modifications.
One cycle involving both loops takes about 24 hours to be completed and is governed by post-translational modifications and may be modulated by the actions of nuclear receptor co-activators and co-repressors.
Typically the type of modification is governed by the type of tissue architecture, for example surface modification of highly organised tissues such as ligament tend to focus on contact guidance techniques, whereas tissues where there is a high degree of cell-matrix or cell-cell interplay focus on extracellular matrix or other biomolecule modifications.
Changes in the epigenetic landscape are governed by various posttranslational histone tail modifications, nucleosome repositioning, and DNA methylation events which collectively allow the control of changes in transcription networks during transitions of satellite cells from a dormant quiescent state toward terminal differentiation.
Although the transcriptional activity of hGR is primarily governed by ligand binding, post-translational modifications also play important roles.
A recent study demonstrated that aminoacylation of mitochondrial tRNAs bearing a CCA tail is regulated by oligoadenylation, catalyzed by the mitochondrial poly(A) polymerase (PAPD1); the steady-state level of this modification is governed by the balance between the activities of PAPD1 and phosphodiesterase 12 (PDE12), and is particularly prominent for tRNALys and tRNASer2 AGY 15.
