Proteins marking

Comparative study of LB films of cytochrome P450 wild type and recombinant revealed similar surface-active properties of the samples. CD spectra have shown that the secondary structure of these proteins is practically identical. Improved thermal stability is also similar for LB films built up from these proteins. Marked differences for LB films of wild type and recombinant protein were observed in surface density and the thickness of the deposited layer. These differences can be explained by improved purity of the recombinant sample. In fact, impurity can disturb layer formation, preventing closest packing and diminishing the surface density and the average monolayer thickness. Decreased purity of... 

Furthermore, addition of lysine to soy protein markedly increased the rate of lipid absorption and addition of arginine to casein slowed lipid absorption. The slowed absorption of lipids in animals fed soy protein is similar to that reported for soluble fibers such as pectin and guar gum that act to lower serum cholesterol concentrations in a number of animal species, including humans. 

One TIRF study found that some membrane proteins behave just oppositely to AChR they avoid the cell/substrate contact regions/ 1 When endothelial cells are grown on a bare glass surface or are brought into suspension, a specific membrane protein marked with antibodies appears all over the cell surface, as evidenced by epi-illumination and TIRF. However, when the cells are grown on (or returned to) a surface coated with their own extracellular matrix material, the protein disappears from the basal (cell/substrate-contacting) side of the cells. 

Proteins that are defective or destined for rapid turnover are often marked for destruction by ubiquitination—the attachment of a small, highly conserved protein, called ubiquitin (see p. 244). Proteins marked in this way are rapidly degraded by a cellular com ponent known as the "proteasome", which is a complex, ATP-dependent, proteolytic system located in the cytosol. 

While chaperonins assist proteins to fold correctly proteasomes destroy unfolded chains by partial hydrolysis, cutting the chains into a random assortment of pieces from 3 to 30 residues in length with an average length of 8 residues/ Proteasomes destroy not only unfolded and improperly folded proteins but also proteins marked for destruction by the ubiquitin system described in Box 10-C. It has been hard to locate true proteosomes in most bacteria. However, they do contain protease particles with similar characteristics2-1 and archaeons, such as Thermoplasma acidophilum, have proteasomes similar to those of eukaryotes.cc... 

Normander, B., Hendriksen, N.B., Nybroe, O. Green fluorescent protein-marked Pseudomonas fluorescens localization, viability, and activity in the natural barley rhizosphere. Appl Environ Microbiol 1999 65 4646-51. 

Q13 Osteomalacia and osteoporosis are complications of celiac disease. The mineral in bone is mainly calcium phosphate a supply of calcium is therefore needed for bone growth and replacement. Calcium is absorbed by active mechanisms in the duodenum and jejunum, facilitated by a metabolite of vitamin D. It is also passively absorbed in the ileum and specific calcium binding proteins are present in the intestinal epithelial cells. Loss of absorptive cells and calcium binding proteins markedly decreases calcium uptake and limits its availability for bone growth and repair. 

Proteasome is a large multisubunit complex in the cytosol that degrades proteins, marked by ubiquitination. Proteolysis requires ATP. 

This appears to be the case for albumin, probably because of the fatty acid content of this protein. Markedly different adsorption isotherms were observed for different albumin preparations, and some isotherms did not appear to reach a plateau adsorption level even at physiological albumin concentrations see upper curve in Figure 5). Removal of the fatty acid by the acid charcoal method of Chen (31) appears to normalize the appearance of the isotherm see the lower curve in Figure 5). Since the fatty acid content of various albumin preparations varies markedly, the variations in apparent adsorption behavior of different albumin preparations appears to be attributable to this cause see Table III). 

Complete amino acid sequences have been determined for those proteins marked by an asterisk. 

STAT, small G-proteins, MARK) Cellular effect... 

The study of DNA and proteins marks the advance of molecular biology. Pharmaceutical research increasingly relies on molecular biology, and it is here that science most directly joins drug... 

FIGURE 8.16 Some types of associations of proteins with membranes. The proteins marked 1, 2, and 4 are integral proteins, and protein 3 is a peripheral protein. Note that the integral proteins can be associated with the lipid bilayer in several ways. Protein 1 transverses the membrane, protein 2 lies entirely within the membrane, and protein 4 projects into the membrane. 

Fibronectin and IgG preadsorption promoted macrophage attachment while all other proteins markedly decreased or prevented attachment. 

The presence of protein in ampicillin has been shown to have a significant effect upon the immunogenicity of the antibiotic (Knudsen et al. 1970). Removal of protein markedly reduced the immunogenicity as well as the antigenicity. Immunogenicity was, however, not completely abolished and low levels of antibody were detected in the rabbits used in the immunization experiments. A similar reduction in immunogenicity and antigenicity of ampicillin preparations (and 6-APA preparations) by reduction of protein levels was shown by Shaltiel et al. (1970, 1971). 

MDM, murine double minute protein with human homolog, neutralizes p53 protein marking it for ubiquitylation (Figure 64). Click for MDM/p53 protein complex rheostat by Eischen CM Lozano G. In FAK (focal adhesion kinase) protein complex, p53 protein is inactive. Click for R2 (Roslin) dismpting FAK/p53 protein complex and liberating p53 protein for action (to block tumor growth) by Golubovskaya VM Ho B Conroy J et al. 

Viral oncoproteins generated by certain adeno-, papilloma-, and polyoma viruses by physical attachment of virally encoded proteins to the retinoblastoma gene product tumor suppressor protein mark that protein for degradation by ubiquiti-nation. Those cells rendered defenseless due to the loss of the rb tumor suppressor gene or its protein RB, succumb to malignant transformation driven by an... 

Figure 1. Three proteins, marked pli, pli, and pli, schematically electrofocused in a column. Each of the three protein components is negatively charged above its respective point and positively charged beneath. For that reason it will move in the electric field until the position in the column is reached where the pH of the pH-gradient is the same as the isoelectric point for that particular protein.

This process is illustrated in Figure 1, which schematically shows how three proteins, marked (pli), (pis) and (pis), are focused in a column. Diffusion counteracts the electrofocusing. As the diffusion coefficient is inversely proportional to the molecular weight, it is understandable that better focusing is obtained with higher molecular weight proteins. 

Addition of low concentrations of various macromolecular polyanions [notably poly-L-glutamate, poly-L-aspartate, or heparin at pH 7.4, or poly(A) at pH 6.5] under conditions that do not result in nonenzymatic precipitation of vesicular secretion proteins markedly enhances... 

In this report, we show that the inhibition of DNA polymerase a may be due to a direct modification of either the enzyme molecule itself or some protein cofactors required for enzyme activity. Recent studies of DNA polymerase a have revealed that the pol3rmerase associates with a tightly boimd primase (5, 6) and that the primase was markedly stimulated by a specific primase-stimulating factor (7). We also found that various basic proteins markedly stimulate the DNA polymerizing activity of DNA polymerase a-primase complex. We describe here the effect of poly(ADP-ribosyl)ation on the activities of the enzymes and the stimulating factors separately. 

On the whole, however, the usual relation— absorption of heat on solution and increase of solubility with temperature— is found much more commonly in protein systems, especially at low ionic strengths. Differ t proteins often differ markedly in heat of solution. The classical method of preparation of edestin involved its crystallization by the gradual cooling of a very warm salt solution of the protein. Marked differential effects of temperature on solubility have been observed for different components among the globulins of normal plasma, notably for y- obulin, and fibrinogen, and have been used already in certain procedures, especially for the purification of fibrinogen (Part VI). 

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