Severing proteins

Interest in vaccine development has centered around the asexual erothrocytic stage of the life cycle, especially the mero2oite. Several proteins associated with these stages have been identified and produced by recombinant techniques (92,93). The most prominent is the MSA-1 protein of the mero2oite. A clinical trial with this protein is being planned (93). 

The sharp bend of DNA at the TATA box induced by TBP binding is favorable for the formation of the complete DNA control module in particular, for the interaction of specific transcription factors with TFIID. Since these factors may bind to DNA several hundred base pairs away from the TATA box, and at the same time may interact with TBP through one or several TAFs, there must be several protein-DNA interactions within this module that distort the regular B-DNA structure (see Figure 9.2). The DNA bend caused by the binding of TBP to the TATA box is one important step to bring activators near to the site of action of RNA polymerase. 

It has also been possible to determine the x-ray structures of classic zinc finger motifs from several proteins bound to specific DNA fragments. We will here describe one such structure containing three zinc fingers from a mouse protein, Zif 268, which is expressed at an early developmental stage of the mouse. Nikola Pavletich and Carl Pabo at the Johns Hopkins University School of Medicine, Baltimore, determined the x-ray structure to 2.1 A resolution of a recombinant polypeptide derived from Zif 268 bound to a 10-base... 

FIGURE 6,37 Ribbon structures of several protein modules utilized in the construction of... 

FIGURE 18.40 The glutamyl carboxylase reaction is vitamin K-dependent. This enzyme activity is essential for the formation of 7-car-boxyglutamyl residues in several proteins of the blood-clotting cascade (Figure 15.5), accounting for the vitamin K dependence of coagulation. 

Organoselenium compounds in particular, once ingested, are slowly released over prolonged periods and result in foul-smelling breath and perspiration. The element is also highly toxic towards grazing sheep, cattle and other animals, and, at concentrations above about 5 ppm, causes severe disorders. Despite this, Se was found (in 1957) to play an essential dietary role in animals and also in humans — it is required in the formation of the enzyme glutathione peroxidase which is involved in fat metabolism. It has also been found that the Incidence of kwashiorkor (severe protein malnutrition) in children is associated with inadequate uptake of Se, and it may well be involved in protection... 

Maciver, S.K. (1991). The actin filament severing protein actophorin promotes the formation of rigid bundles of actin filaments crosslinked with a-actinin. J. Cell Biol. 115, 1621-1628. 

While it has been known for many years that the N-terminal presequence is sufficient to promote mitochondrial targeting and assembly, the subsequent interaction of the precursor molecule with the outer mitochondrial membrane and the uptake of the protein is still an area of active research. There seems little doubt, however, that there are proteins on the outer mitochondrial membrane which are required for the import process. The function of these proteins is uncertain, but they may act as receptors with the subsequent transfer through the membrane at proteinous pores located at contact sites between the inner and outer membranes. Several proteins have been identified which seem to play an important role as either receptor proteins or part of the import channel (Pfanner et al., 1991). Again, not all proteins seem to depend on this mechanism. Cytochrome c, which is loosely associated with the outer aspect of the inner mitochondrial membrane, can cross... 

The functions of a large proportion of the proteins encoded by the human genome are presently unknown. Recent advances in bioinformatics permit researchers to compare amino acid sequences to discover clues to potential properties, physiologic roles, and mechanisms of action of proteins. Algorithms exploit the tendency of nature to employ variations of a structural theme to perform similar functions in several proteins (eg, the Rossmarm nucleotide binding fold to bind NAD(P)H,... 

The electrochemical potential difference is used to drive a membrane-located ATP synthase which in the presence of P + ADP forms ATP (Figure 12-8). Scattered over the surface of the inner membrane are the phos-phorylating complexes, ATP synthase, responsible for the production of ATP (Figure 12-1). These consist of several protein subunits, collectively known as F, which project into the matrix and which contain the phosphorylation mechanism (Figure 12-8). These sub-... 

Initiation Involves Several Protein-RNA Complexes (Figure 38-6)... 

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