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Myelin, amino acids

There is a second family of small lipid-binding proteins, the P2 family, which include among others cellular retinol- and fatty acid-binding proteins as well as a protein, P2, from myelin in the peripheral nervous system. However, members of this second family have ten antiparallel p strands in their barrels compared with the eight strands found in the barrels of the RBP superfamily. Members of the P2 family show no amino acid sequence homology to members of the RBP superfamily. Nevertheless, their three-dimensional structures have similar architecture and topology, being up-and-down P barrels. [Pg.70]

Antibodies typically are able to recognize peptide sequences as small as 5-6 amino acids in length. For instance, IgE auto-antibodies were found to have clinical significance in multiple sclerosis by binding specifically to short 5- and 6-amino acid epitopes on the surface of myelin proteins (Mikol et al., 2006). [Pg.746]

The MBPs are extrinsic proteins localized exclusively at the cytoplasmic surface in the major dense line (Fig. 4-11), a conclusion based on their amino acid sequence, inaccessibility to surface probes and direct localization at the electron microscope level by immunocytochemistry. There is evidence to suggest that MBP forms dimers, and it is believed to be the principal protein stabilizing the major dense line of CNS myelin, possibly by interacting with negatively charged lipids. A severe hypomyelination and failure of compaction of the major dense line in MBP deficient shiverer mutants supports this hypothesis (Table 4-2). [Pg.60]

Members of this family of molecules may have only one Ig-like domain, as is the case for the myelin protein P0, or, as for most of the family, have many Ig domains. In addition to the subclassification of Ig domains into V-, C- and C2-like domains, Ig family members can be broadly divided into three general classes [8] (a) those that have only Ig-like domains (b) those that have Ig domains and additional domains that resemble regions of the ECM component fibronectin, termed FN-like domains and (c) those that have Ig domains and motifs other than FN-like domains. Moreover, any one Ig family member may have many isoforms, which may differ in the length of the cytoplasmic domain, in their post-translational modifications and whether they are membrane-spanning or glycosylphos-phatidylinositol (GPI)-anchored proteins (see Box 3-1). Also, additional amino acid sequences inserted in the extracellular domain may distinguish isoforms of a particular IgCAM. While it is not known how the majority... [Pg.112]

FIGURE 7-7 Structure of the P0 glycoprotein protomer. (A) In this ribbon diagram of the extracellular domain of P0, each P strand is labeled with a letter and two antiparallel P sheets are formed. The disulfide bridge is indicated in dark orange and a hypothetical path for disordered amino acids 103-106 is shown in black in the FG loop. (B) Lattice formation by P0. A view of the intraperiod line, or extracellular apposition, of myelin in the PNS. The orange tetramer sets emanate from one bilayer and the blue tetramer interacts with all four of them. This is a view perpendicular to the plane of the myelin membrane. [Pg.119]

Rostami, A., Gregorian, S. K., Brown, M. J. and Pleasure, D. E. Induction of severe experimental autoimmune neuritis with a synthetic peptide corresponding to the 53-78 amino acid sequence of the myelin P2 protein. J. Neuroimmunol. 30 145-151,1990. [Pg.627]

Other leukodystrophies are associated with the lysosomal and peroxisomal disorders in which specific lipids or other substances accumulate due to a deficiency in a catabolic enzyme - for example Krabbe s disease, meta-chromatic leukodystrophy (MLD) and adrenoleuko-dystrophy (ALD) [1,2]. (These are discussed in detail in Ch. 40.) Similarly, disorders of amino acid metabolism can lead to hypomyelination - for example phenylketonuria and Canavan s disease (spongy degeneration) [1, 2, 25] (Ch. 40). The composition of myelin in the genetically... [Pg.647]

Phenylketonuria AR Phenylalanine hydroxylase White matter is up to 40% deficient in myelin hypomyelination may be caused by inhibition of amino acid transport and/or protein synthesis by the high level of phenylalanine that accumulates 1, Ch. 40... [Pg.647]

Imbalances of brain amino acids may hinder the synthesis of brain lipids, leading to a diminution in the rate of myelin formation 671... [Pg.667]

Imbalances of brain amino acids may hinder the synthesis of brain lipids, leading to a diminution in the rate of myelin formation. Decreases of lipids, proteolipids and cerebrosides (Ch. 3) have been noted in several of these syndromes, e.g. maple syrup urine disease, when intra-myelinic edema is a prominent finding, particularly during the acute phase of metabolic decompensation [9]. Pathological changes in brain myelin are common, especially in infants who die early in life. The fundamental... [Pg.671]

The most hydrophobic integral membrane proteins can be extracted into organic solvents such as mixtures of chloroform and methanol. One such proteolipid protein, the 23.5-kDa lipophilin, accounts for over half the protein of myelin.57 182 The purified protein from rat brain contains 66% of nonpolar amino acids and six molecules of covalently bound palmitic acid and other fatty acids per peptide chain in thioester linkage to cysteine side chains. This protein evidently has four transmembrane helical segments with the six fatty acid chains incorporated into the membrane bilayer. It also has cytoplasmic and extracellular loops, one of which binds inositol hexakisphosphate (Ins P-6). (Fig. 11-9).183 The myelin proteolipid is an essential component of the myelin sheath and defects in this protein are associated with some demyelinating diseases57 which are discussed in Chapter 30. [Pg.401]

Because ALBP is related to several proteins of known structure, molecular replacement is an attractive option for phasing. The choice of a phasing model is simple here just pick the one with the amino-acid sequence most similar to ALBP, which is myelin P2 protein. Solution of rotation and translation functions refers to the search for orientation and position of the phasing model (P2) in the unit cell of ALBP. The subsequent paper provides more details. [Pg.175]

The initial model of ALBP was built by simply putting the amino acid sequence of ALBP into the molecular structure of myelin P2 protein. After a 20-step rigid-body refinement of the positions and orientations of the molecule, crystallographic refinement... [Pg.178]

Increased production of metabolites of phenylalanine that inhibit synthesis of a variety of substances required for normal brain growth Inhibition of TV-methyl-D-aspartate receptors, which are involved in memory and learning Competitive inhibition of transport of other amino acids required for protein synthesis Impaired polyribosome formation or stabilization Reduced synthesis/increased degradation of myelin Decreased formation of norepinephrine and serotonin Altered myelin structure and function... [Pg.206]

Fujinami RS, Olds tone MB (1985) Amino acid homology between the encephalitogenic site of myelin basic protein and vims Mechanism for autoimmunity. Science 230 1043—1045. [Pg.253]


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See also in sourсe #XX -- [ Pg.231 ]




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