Yeast Set Proteins Interact with Polypeptides Traversing the Endoplasmic Reticulum Membrane

Summary We show by photocross-linking that nascent secretory proteins, during their passage through the endoplasmic reticulum membrane of S. cerevisiae, are in physical contact with Sec6lp and Sec62p, two genetically identified membrane proteins that are essential for in vlvo translocation. Sec6lp seems to be in continuous contact, whereas Sec62p is involved only transiently. Translocation comprises both ATP-dependent and -independent phases of interaction with the Set proteins. The results suggest a direct role of the Set proteins in translocation

BEAM TESTS OF THE ZEUS BARREL CALORIMETER

A fully compensating uranium-scintillator calorimeter was constructed for the ZEUS detector at HERA. Several of the barrel calorimeter modules were subjected to beam tests at Fermilab before shipping them to DESY for installation. The calibrations of the modules used beams of electrons and hadrons, measuring the uniformity of the response, and checking the resolution. The runs also provided opportunity to test a large fraction of the actual ZEUS calorimeter readout system in an integrated beam environment more than one year before HERA turn on. The experiment utilized two computer controlled mechanical structures. one of which was capable of holding up to four modules in order to study shower containment, and a magnetic spectrometer with a high resolution beam tracking system. During two running periods, beams of 6 to 110 GeV containing e, mu, pi, and pBAR were used. The results show energy resolutions of 35%/square-root E for hadrons and 19%/square-root E for electrons, uniformities at the 1% level, energy nonlinearity less than 1%, and equal response for electrons and hadrons