CSL proteins

Fig. 12.2. Model of Notch signalling. The Notch protein is a ligand activated transmembrane receptor which is subject to proteolysis of the intracellular domain upon ligand binding. The nature of the protease involved is still a matter of debate. The proteolytically released intranceUu-lar domain of Notch (NICD) translocates into the nucleus where it interacts with a family of transcription factors, the CSL proteins, resulting in a change in transcription of target genes.

Table 3.4. The cellulose synthase-like (CSL) proteins of Arabidopsis...

CSLC, CSLD, and CSLE. Rice appears to lack the CSLG and CSLB families and possess two additional families CSLF CSLH. Monocots and dicots do possess different cell wall architectures (Carpita and McCann 2000). Whether this classification of the CSLs truly represents a division between the monocots and dicots requires further study since biochemical functions have not yet been ascribed to the CSL proteins. Interestingly, the C5Ls form two separate clades when compared with the CESA genes from plants and other organisms. The... 

The subsequent advance was rather fortuitous and rested more with serendipity than with scientific logic. A search was made for cheaper more effective replacements for casein hydrolysate. Amongst the tested materials was com steep liquor (CSL). CSL is a by-product of the manufacture of starch from maize kemals. Whole maize is incubated in warm water, at 50°C acidified with SO2. Thermophilic bacteria hydrolyse proteins and other components of the kemals, thereby loosening the starch granules. These are removed, leaving behind the steep liquor which is used to treat further maize kemals. Ultimately, the liquor is too viscous to re-use and the liquor is concentrated and used as cattle feed. It was this material that was used for penicillin fermentation. Surprisingly, the yield of penicillin increased by a further 5-10 fold giving yields of 50-100 ig ml. 

The arrival of the action potential at the presynaptic terminal opens voltage-dependent Ca ion channels in the plasma membrane so that the Ca ions enter the cytosol down their concentration gradient. This results in activation of a Ca -binding cytosolic or a membrane protein. This facilitates movement of the vesicles to the membrane and formation of a fusion pore through which the neurotransmitter is discharged into the synaptic cleft (i.e. exocytosis). This occurs within about 0.1 ms of the arrival of the depolarisation (Figure 14.8). The process of exocytosis lasts for only a short time, since the Csl ion concentration in the cytosol is rapidly lowered due to the ion extrusion from the cell (Appendix 14.3). 

Effects of Surfactants. Two types of surfactants [sodium stearoyl lactylate (SSL) and calcium stearoyl lactylate (CSL)] at two concentrations (0.2 and 0.4%) were added to soy flours to study the effect of surfactants on the texturization properties of soy flours. An extrusion helper (Tolutein, yeast cell protein) was also included at two concentrations (1 and 2%) in this study because of its behavior similar to a surfactant upon extrusion. 

Figure 8. Exterior morphologies of extrusion texturized surfactant-added soy flours. Control, no surfactant added product Tolutein, yeast protein CSL SSL. Note the effect of surfactant on the diameter and surface smoothness of extrudates. (Mag. J.5X.)...

Readily available proteins have been suggested as reference compounds as well. A mixture of the peptide MRFA and myoglobin has been nsed for calibration by Thermo Finnigan. The use of a protein solntion rather than Csl/Nal or PPG as a reference compound is sometimes reconunended for protein analysis, because the multiple-charge ions of proteins may behave differently from single-charge cluster ions [28]. 

Addition to purified and diluted solutions of xanthan. For this study, it was necessary to prepare a non-aggregated xanthan solution which was obtained by extensive ultrafiltration of a commercial xanthan sample which was initially non-aggregated. The absence of aggregation was confirmed by the Huggins constant which was 0.4 and the intrinsic viscosity which was 6.7 m kg. This corresponds to a molecular weight of 4.8x10 daltons. This xanthan solution was adjusted at a polymer concentration of 0.4 g.l"l in a protein-rich solution such as com steep liquor (CSL). Before use, the com steep solution was centrifuged and only the clear supernatant was added to the xanthan solution. The solvent was 0.1 M sodium chloride and the ratio of protein to xanthan was 10% (w/w). 

According to fermentation conditions and to downstream processes, the nature and the concentration of proteins in broths may be quite different. Table I indicates the total concentration of proteins, i.e intracellular proteins and proteins used as growth factors during fermentation (CSL, yeast extract). Furthermore, the pymvate content of the xanthan molecule also depends on fermentation conditions. 

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