Intracellular control

One should note overall, that while some of these suggested mechanisms may in the future prove to have a role in the control of smooth muscle contraction, in chemically skinned preparations maximum force development follows activation by the MLCK active subunit in extremely low Ca " ion concentrations. The conclusion can hardly be avoided that phosphorylation alone is sufficient for activation, and if another mechanism is involved, it is not necessary for the initial genesis of force. If such mechanisms are operative, then they might be expected to run in parallel or consequent to myosin phosphorylation. A possible example of this category of effect is that a GTP-dependent process (G-protein) shifts the force vs. Ca ion concentration relationship to lower Ca ion concentrations. This kind of mechanism calls attention to the divergence of signals along the intracellular control pathways. 

R. R. Schmidt (1966). Intracellular control of enzyme synthesis and activity during synchronous growth of Chlorella. In I. L. Cameron and G. M. Padilla (Eds), Cell Synchrony Studies in Biosynthetic Regulation, Academic Press, New York, pp. 189-198. 

Michaelis-Menten kinetics and empirical kinetic parameters can be joined to give pieces of information on optimum (diffusion-controlled) catalytic kinetics, just assuming that optimum turnover means use of the best catalytic center species and half substrate saturation. This holds for small substrate concentrations, probably subject to intracellular control or limited take-up. Then ... 

Henson, P.M., Schwartzmann, N.A. and Zanolari, B. (1981). Intracellular control of human neutrophil secretion. II. Stimulus specificity of desensitisation induced by six different soluble and particulate stimuli. J. Immunol. 127, 754-759. 

Harashima H, Shinohara Y, Kiwada H. Intracellular control of gene trafficking using liposomes as drug carriers. Eur J Pharm Sci 2001 Apr 13(l) 85-89. 

The body tends to use allosteric regulation for rapid intracellular control mechanisms that work on a time scale of a few seconds or less. Covalent modification tends to be used for both intra- and extracellular mechanisms and, even within cells, is often part of the signaling stimulated by extracellular signals. Although some systems based on covalent modifications respond very rapidly, others respond more slowly, with effects being seen in a matter of minutes rather than seconds. 

Once again, the level of the cations is controlled by membrane processes and metabolism from bacteria to animals and plants so that the same dependences on cations are found in all forms of life. For example, intracellular control of glycolysis is partly through the magnesium and potassium concentrations. Here we observe, much as has been seen in the chemistry of zinc, iron, cobalt, and copper, that biology has few variants on particular systems but these systems are chosen with remarkable ingenuity. 

Bemdt, N., Protein dephosphorylation and the intracellular control of the cell number. Eront. BioscL, 4, 22, 1999. 

Landesberg, A., Markhasin, V.S., Beyar, R. et al.. Effect of cellular inhomogeneity on cardiac tissue mechanics based on intracellular control mechanisms. Am. J. Physiol, 270, HI 101-H1114, 1996. 

The Cystatins are ubiquitous proteinase inhibitors of cysteine proteases that regulate various biolc ical and pathological processes by inhibition of cysteine protease activity. Cystatin is secreted by human mononuclear phagocytes and durii inflammatory processes its expression is down modulated which, in turn contributes to increased cytsteine protease activity. In addition, the study of cystatin in DC maturation and MHC molecule processing si ested that cystatin plays a role in the intracellular control of invariant chain degradation and antigen presentation. ... 

For process modeling it is not possible to understand all intracellular control loops. But in many cases we can formulate model hypothesis on the final effect of intracellular control. Some assumptions have already been done... 

Chapter 3 is devoted to phototrophic processes modeling. The model approach includes the level of metaboHc fluxes and of the intracellular control. The appropriate balance equations and kinetics are outlined. The specific features, such as photosynthesis, carbon uptake, and carbon partitioning, are described. Dynamic description of the complex reactions of the cells to environmental changes is also discussed with some examples. The objective of this chapter is to give the basic biological background, to deduce, step by step, the model s governing equations, and to present simulation results with realistic parameter values. 

Chen, M., He, X., Wang, K., He, D., Yang, S., Qiu, P., and Chen, S. (2014) A pH-responsive polymer/mesoporous silica nano-container linked through an acid deavable linker for intracellular controlled release and tumor therapy... 

Bernardos, A., Mondragdn, L., Aznar, E., Marcos, M.D., Martinez-Mdnez, R., Sancenon, F., Soto, J., Bamt, J.M., Perez-Paya, E., Guillem, C., and Amoros, P. (2010) Enzyme-responsive intracellular controlled release using nanometric silica mesoporous supports capped with saccharides . ACS JVflwo, 4 (11), 6353-6368. 

Mortera, R., Vivero-Escoto, J., Slowing, IJ., Garrone, E., Onida, B., and Lin, V.S.Y. (2009) Cell-induced intracellular controlled release of membrane impermeable cysteine from a mesoporous silica nanoparticle-based drug delivery system. Chem. Commun., (22),... 

C.-W., and Lin, VS.Y. (2009) Photoinduced intracellular controlled release drug delivery in human cells by gold-capped mesoporous silica nanosphere. J. Am. Chem. Soc,... 

Chen, P.-J., Hu, S.-H., Hsiao, C.-S., Chen, Y.-Y., Liu, D.-M., and Chen, S.-Y. (2011) Multifunctional magnetically removable nanogated lids of Fes04-capped mesoporous silica nanoparticles for intracellular controlled release and MR imaging. /. Mater. Chem., 21 (8), 2535-2543. 

---