Z-protein

Although the distribution of these receptors is widespread in the brain, they are found postsynaptically in high concentrations in the hippocampus, septum and amygdala and also on cell bodies of 5-HT neurons in the Raphe nuclei. They are negatively coupled, via Gj/o/z proteins, to adenylyl cyclase such that their activation reduces production of cAMP. In turn, this leads to an increase in K+ conductance and hyperpolarisation of... 

Puhan, Z., Protein standardization as an international issue, in Advances in Membrane Technology for Better Dairy Products, Bulletin International Dairy Federation, 311, 1996, p. 5. 

Decreased Storage of Unconjugated Bilirubin in Cytosol (Decreased Y and Z Proteins)... 

Ohashi and Maruyama (1979) isolated a 55-kDa protein from chicken breast muscle that formed a lattice structure with a periodicity of 8 nm. This protein, termed Z protein, is the only known candidate for the lattice structure of Z lines. Although the molecular weight of Z protein is similar to that of desmin, the amino acid compositions are entirely different. The Z protein is located in the interior of Z lines as revealed by an immunofluorescent technique (Ohashi et al., 1982). 

Thus, the overall regulatory pattern is as follows A bacterium growing in a medium without lactose does not make either the lac z or lac y product because the repressor that is made is bound to the operator and prevents synthesis of lac mRNA. The cell grows by utilizing whatever other carbon source is available. If lactose is added (and if glucose is absent see below), basal level lac y and lac z proteins bring the lactose into the cell and convert it to allolactose. As a result, the repressor is inactivated, RNA polymerase binds to the promoter, and synthesis of lac mRNA begins. Lac mRNA synthesis continues until the lactose is exhausted, in which case the inactive repressor would be reactivated and repression reestablished. 

It has also been proposed that hpids, Upid metabolites and cytosolic lipid-binding proteins interact to regulate sterol biosynthesis [199] (see also Chapter 3). Under this model, the accumulation in cells of certain hpids or free hpid intermediates inhibits sterol biosynthetic enzymes. The level of the binding protein for a particular Upid would determine the threshold concentration of Upid needed to produce inhibition [199]. Such a mechanism would allow coordination between the biosynthesis of sterols and other Upids. Fatty acyl-CoAs and Z-protein, the fatty acyl-CoA-binding protein, may modulate HMG-CoA reductase activity [199-201] since physiological... 

Siefermann-Harms D and AngerhoferA(1995) An 02-barrierin the hght-harvesting Chl-o/Z)-protein complex LHCII protects chlorophylls and carotenoids from photooxidation. In Mathis P (ed) Photosynthesis From Light to Biosphere, Vol IV, pp 71-74. Kluwer Academic Publishers, Dordrecht... 

Adam Z. Protein stability and degradation in chloroplasts. Plant Mol Biol 1996 32(5) 773-783. 

Jones CA, Ng J, Peterson AJ, Morgan K, Simon J, Jones RS. The Drosophila esc and E (z) proteins are direct partners in polycomb group-mediated repression. Mol Cell Biol. 1996 18 2825-34. 

Synthesis of triacylglycerols requires the enzyme diacylglycerol acyltransferase (EC 2.3.1.20). The enzyme is particulate and has been studied in many mammalian tissues (O Doherty, 1978). In some cases activity is stimulated by the additon of phosphatidylcholine (O Doherty et al, 1974) and there is also evidence that the Z protein may be involved in stimulating acyltransferase activity (O Doherty and Kuksis, 1975). 1,2-Isomers of diacylglycerol are about twice as effective as 2,3-isomers. The enzymes show little chain-length specificity, however (e.g. Hill etal, 1968). 

Fibronectin A family of closely related adhesion glycoproteins, Mj 200,000-250,000, which arise by the alternative splicing of the precursor mRNA. F. is found both as a cell surface protein of the extracellular matrix (also known as Cell Surface Protein, Galac-toprotein A, Large External Transformation Sensitive Protein, Surface Fibroblast Antigen, and Zeta or Z Protein), and in plasma. Plasma fibronectin is incorporated into fibrin clots and is cross-linked to the fibrin, probably via a Gln-Lys transamidation reaction. 

Vodrazka, Z. Protein interactions. XIX. Interaction of serum albumin with fluorescein dyes. Collect. Czech. Chem. Commun. 1960,25,4KM19. 

Both non-esterified fatty acids and acyl-CoAs are capable of binding to distinct cytosolic proteins known as fatty acid binding proteins (FABP). The best known of these is the Z-protein of liver. These small molecular weight (about 14kDa) FABPs have been suggested to function for intracellular transport or to provide a temporary binding site for potentially damaging compounds such as acyl-CoAs (section 5.3.3). 

Other fatty acid binding proteins, such as the Z-protein, have been described in sections 3.3.1 and 5.3.3. Their function is thought to be to transport fatty acids and acyl-CoAs within cells rather than in the blood. This is important, not only because of the problem of water insolubility but because of the disruptive detergent effects of these substances in the free state. 

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