Distinct compartmentalization of TGN46 and beta 1,4-galactosyltransferase in HeLa cells.

The Golgi proteins, TGN46 and GalT, were characterized in human HeLa cells using specific polyclonal and monoclonal antibodies. A bacterially expressed soluble recombinant TGN46 protein was used to raise rabbit polyclonal antibodies and used to probe HeLa cell extracts. Human TGN46 had an apparent molecular mass of 100 to 120 kDa which reflects extensive glycosylation. Epifluorescence light microscopy indicated substantial colocalization of TGN46 and GalT. However, confocal laser microscopy and three-dimensional reconstruction of double-labeled HeLa cells revealed large areas of colocalization but also specific differences in the distribution of these two proteins within the Golgi apparatus. Importantly, quantitative immunoelectron microscopy showed that there was little overlap between the distribution of GalT and TGN46. Approximately 75% of GalT was in the Golgi stack, whereas 80% of TGN46 was detected in tubules. Distinct GalT-positive regions within the Golgi cisternal stack were not labeled for TGN46.

Pulse-length scaling of laser damage at 249 nm in oxide and fluoride multilayer coatings.

We have measured laser damage thresholds of a variety of fluoride-based multilayer coatings at 249 nm by using pulse lengths between 450 fs and 25 ns. Rare-earth fluoride materials yield coatings with damage resistance approximately three times greater than conventional oxide multilayers. In the scaling law, where the damage threshold is proportional to the nth power of the pulse length, the value of n changed between 1 and 0.25 over the range of pulse lengths employed.