Phosphorylation enhanced

Smith WW, Margolis RL, Li X, Troncosco JC, Lee MK, et al. 2005. A-Synuclein phosphorylation enhances eosinophilic cytoplasmic inclusion formation in SH-SY5Y cells. J Neurosci 25 5544-5552. 

It has been demonstrated that phosphorylation of LHC causes the detachment of a fraction of it from PS II and its lateral migration in the membrane to become incorporated into PS I [134-136]. It has indeed been shown that the fluorescence quenching caused by LHC phosphorylation is qualitatively different from spillover, because only LHC is quenched, not PS II [136], and Fq as well as are quenched [136,137]. The phosphorylation of LHC and/or of other thylakoid polypeptides may have more complex effects, and their interactions are far from being understood. It has been reported that protein phosphorylation enhances PS I-de-pendent cyclic photophosphorylation even under light saturation conditions [133], which could not be explained merely on the basis of PS I antenna enlargement. 

It is a very interesting to know the role of electrical potential under conditions in which ApH across the thylakoid membrane is removed and electrical potential is not damaged, so as to eliminate the enhancement of iipH induced by a decline of electrical potential. Such a condition was obtained by the addition of Nig. or NHi Cl. The result was shown in Fig.5. Nigericin, at such concentration that electron transport is uncoupled from phosphorylation, enhanced the light-induced swelling of thylakoid membrane significantly. This effect was inhibited by Val. It could be deduced that in addition to the H accumulated inside the thylakoid membranes enhanced by decline of electrical potential, electrostatic repulsion between membranes... 

One such hypotheses submits that most antidepressants enhance the expression of cyclo-AMP response element binding protein (CREB), which is a transcription factor that after phosphorylation binds to cyclo-AMP response elements localized in the promoter region of many genes including that coding for brain... 

As mentioned above, many transcription factors are not always active. Rather the activity of transcription factors is often achieved by induced reversible modification. Most frequently is the addition of phosphate groups (phosphorylation) to Ser, Thr, or Tyr residues. For the AP-1 component c-Jun the phosphorylation at Ser63 and Ser73 enhances activity when cells are subjected to stress, e.g. radiation. Phosphorylation is, however, dispensable for c-Jun-dqDendent tissue homeostasis in the liver, indicating that certain activities do not require the regulatory enhancement. Jun-N-teiminal kinase and a kinase called RSK or p38 catalyze the phosphorylation of AP-1. 

Phosphorylation of HSF substantially enhances the transcriptional activity of HS gene expression which may be up to 100-fold of basal levels after HSFl binds to the promoter element. Heat shock will increase the C-terminal-domain-kinase activity in cell extracts, and this action may enhance the activity of RNA polymerase II that is bound to HS genes (Legagneux et al., 1990). Whether this kinase activity also affects HSFl phosphorylation is not known, but increased HS gene expression appears to occur as long as HSFl is bound to the promoter region. The CTD kinase complex contains multiple proteins, and it is quite possible that one or more of these proteins is also regulated by stress. 

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