Showing papers by "Yu Huang published in 1994"

Glycosylation of shaker potassium channel protein in insect cell culture and in xenopus oocytes

Abstract: We have studied the glycosylation of Shaker K+ channel protein made in two expression systems: an insect cell culture line and amphibian oocytes. In both systems, two potential sites for N-linked glycosylation were modified. The modified sites were located between the first and second putative transmembrane segments, S1 and S2. Although the same sites appeared to be glycosylated in both systems, the fraction of protein glycosylated and the size, structure, or composition of the oligosaccharide chains added were quite different. The results indicate that the S1-S2 loop is extracellular, consistent with a cytoplasmic location for the N-terminus and a transmembrane disposition for hydrophobic segment S 1. We have also shown that glycosylation occurs in two stages in oocytes, generating an immature and a mature form of Shaker protein. However, glycosylation is not required either for the assembly of functional channels or for their transport to the cell surface.

Comparison of transport scattering and single‐particle relaxation times in modulation‐doped heterostructures

Abstract: The transport scattering and single‐particle relaxation times which characterize a two‐dimensional electron system have been investigated by using thermal neutron irradiation. The ratios of transport scattering time to single‐particle relaxation time are observed to vary from 1.7 to 7.8 depending on the electron density. A decrease in single‐particle relaxation time is found while the transport scattering time increases as the electron concentrations increase. These phenomena are relevant to the Hall plateau broadening and enhancement of Shubnikov–de Haas oscillations in such an experiment.