Abstract
CELL BIOLOGY The intracellular transport of membrane proteins requires cellular machinery that recognizes targeting signals that may be present within the cyto-plasmic, membrane, or extracellular domains of the protein. But some proteins contain multiple targeting signals, which need to be decoded sequentially to execute the correct protein itinerary. Anderson et al. have examined the signals in NgCAM, a cell adhesion molecule that is generally found in the axonal membrane of neurons, but is first transported to the dendrites. When expressed in an epithelial cell line, NgCAM is transported to the basolateral plasma membrane and then transcytosed to the apical surface, where it remains despite multiple rounds of endocytosis and reinsertion into the apical membrane. Why then, after endocytosis, does the protein not go back to the basolateral surface? The signal for baso-lateral targeting resides in the cytoplasmic domain of NgCAM and is recognized by an adaptor protein that ensures delivery of newly synthesized protein to the basolateral surface. This signal is masked by phosphorylation of a key tyrosine residue, which uncovers a cryptic apical targeting signal in the extracellular domain and also maintains the protein within a recycling cycle at the apical surface. — SMH J. Cell Biol . 170, 595 (2005).
Highlights
The intracellular transport of membrane proteins requires cellular machinery that recognizes targeting signals that may be present within the cytoplasmic, membrane, or extracellular domains of the protein
More hurricanes may occur in the South Atlantic in the future. — HJS
Many an immunology undergraduate’s headache can be traced to memorizing the intricacies of the complement system.Three activation pathways lead to the generation of the C3 converting enzymes, which are responsible for generating the effector molecules that carry out crucial host defence functions.As a result, the complement system is a target for viral and bacterial evasion strategies
Summary
In the interests of conservation, historical research, and attribution, paintings in museums may be subjected to a barrage of scientific probes, each of which is sensitive primarily to surface or subsurface features; sometimes, small samples are physically removed from the painting for analysis. The development of techniques that are nondestructive and noninvasive is desirable and necessary when it comes to examining old and delicate pieces.The optical interferometric technique of optical coherence tomography (OCT) is usually associated with the three-dimensional A 50-year-old test painting and a spot imaging of biological samples, the inner (inset) where new varnish was applied structure of the eye. Be used for the noninvasive examination of paintings to provide high-resolution and dynamic imaging capabilities for visualizing the structures of layers of varnish, layers of paint, and even the preliminary sketches underneath. This imaging technique should prove to be a useful tool for the conservation and attribution of art.
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