Projective mapping

Karrasch, S., Bullough, RA., Ghosh, R. 8.5-A projection map of the light-harvesting complex I from Rhodospir-illum rubrum reveals a ring composed of 16 subunits. EMBO J. 14 631-638, 1995. 

Fig. 5. Image and optical diffraction pattern of praseodymium-induced crystals, (A). Crystallization was induced with 8 PrCU. Doublet tracks so prominent in vanadate-induced crystals are not evident in crystals induced with lanthanides. This results in an approximate halving of the A-axis of the unit cell. Magnification x 222000. (B) The image of the superimposed top and bottom lattices of the flattened cylinder give rise to two separate diffraction patterns. (C) Projection map of praseodymium-induced crystals. Map scale 0.55 mm per A. From Dux et al. [119].

The projection map of the unstained frozen-hydrated three-dimensional crystals was compared with the map of negatively stained crystals [141,142] to define the densities associated with the intramembranous domains. The ten transmembrane helices were predicted to be arranged in two crescent shaped rows that provide intramembranous contacts between ATPase molecules. The scheme is entirely speculative and with few exceptions there is no clear relationship between the density contours seen in the map and the proposed transmembrane helices. 

Fig. 3.6 (a) Stereographic projection map of a (001) oriented cubic crystal. The facet sizes reflect approximately those of the field ion image of a fee crystal. 

Remark 9.7. It follows from the proof of the lemma that the schemes S X S and S x S x 5 S satisfy the conditions of 9.1. Further we get various commutative diagrams involving lifts of Frobenii and projection maps. This will allow us to use descent arguments. 

S. Karrasch, P.A. BuUough, R. Ghosh, The 8.5-Angstrom Projection MAP of the Light-Harvesting Complex-1 from Rhodospirillum rubrum Reveals a Ring Composed of 16 Subunits , EMBO J., 14,631 (1995)... 

Figure 3. The projection map of bovine rhodopsin at 9 A resolution. One unit cell contains four rhodopsin molecules. Two rhodopsin molecules have been circled. The density map shows four individual peaks, which were interpreted as four individual helices orientated almost perpendicular to the membrane. The arc-shape of density was assigned to the remaining three tilted helices. Reprinted by permission from Nature (1993) 362, 770-772. Copyright 1993 Macmillan Magazines Ltd.

The most recent projection map of bovine rhodopsin is to 5 A resolution. Two-dimensional crystals were obtained of bovine rhodopsin that showed p22 2 symmetry. From this, electron diffraction patterns could be taken which gave an improved projection map, shown in figure 6. 

There are several observable differences between the 1995 and 1997 projection structures. Firstly, the curve of electron density towards helix 5 is longer in the 1997 map, with a more defined peak of density in this region. Therefore, there is more density between helices 3 and 5 than predicted in previous projection maps. Secondly, the tilt (to the vertical) on helix 5 has been underestimated. Earlier projection maps " identified helix 5 as a clear peak, suggesting that helix 5 should be untilted. However, the 1997 projection map indicates an elongated peak for helix 5, which suggests that helix 5 has a well-defined tilt. Finally, electron density is now detected between helices 6 and 2 and between helices 6 and 7. The density between helices 6 and 7 may indicate that helix 7 is perturbed towards the extracellular side. This perturbation in helix 7 was predicted from modelling studies as early as 1986. 

Salo, K., Horwath, A., (1999) Minnesota agri-power project (MAP). In Power Production from Biomass HI, Gasification Pyrolysis R D D for Industry, (Ed. by K. Sipila M. Korhonen), VTT Symposium 192, VTT Espoo. 

Gussing F, Bohm S (2004) NQOl activity in the main and the accessory olfactory systems correlates with the zonal topography of projection maps.Eur J Neurosci 19(9) 2511—2518 Hanson MG, Landmesser LT (2004) Normal patterns of spontaneous activity are required for correct motor axon guidance and the expression of specific guidance molecules.Neuron... 

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