Citation for published item:tmesD F vF nd edmsD gF tF nd folmD gF nd frgD hF nd gollierD F nd pri § s § i¡ D F nd qrepioniD pF nd rrrisD uF hF wF nd ryettD qF nd tonesD F nd uresD eF nd wkD tF nd winiD vF nd yrpenD eF qF nd rkinD sF F nd herouseD F gF nd teedD tF F nd ddellD hF gF @PHIPA 9wehnohemistry X opportunities for new nd lener synthesisF9D ghemil soiety reviewsFD RI @IAF ppF RIQERRUF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

The endoplasmic reticulum (ER) is an important site for protein folding and maturation in eukaryotes. The cellular requirement to synthesize proteins within the ER is matched by its folding capacity. However, the physiological demands or aberrations in folding may result in an imbalance which can lead to the accumulation of misfolded protein, also known as “ER stress.” The unfolded protein response (UPR) is a cell-signaling system that readjusts ER folding capacity to restore protein homeostasis. The key UPR signal activator, IRE1, responds to stress by propagating the UPR signal from the ER to the cytosol. Here, we discuss the structural and molecular basis of IRE1 stress signaling, with particular focus on novel mechanistic advances. We draw a comparison between the recently proposed allosteric model for UPR induction and the role of Hsp70 during polypeptide import to the mitochondrial matrix.

This paper reports a study of the spontaneous precipitation of calcium carbonate from aqueous solutions which are very supersaturated with respect to calcite, both in the absence of inhibitors, and in the presence of triphosphate as inhibitor. The sequence of events during precipitation is governed strongly by the initial supersaturation, t h e temperature, and t h e presence or absence of triphosphate.At high supersaturation, the first-formed phase is an amorphous calcium carbonate. It is observed only above a well defined ionic activity product, is homogeneously nucleated, and its formation is not inhibited by triphosphate. Over the temperature range 289-333 K, this amorphous phase has a solubility product, K , , defined by the equation : log K1 = (1247.0/T) -10.224At concentrations insufficient to produce the amorphous phase, t h e first-formed solid nucleates heterogeneously. In t h e absence of triphosphate it is calcite. In the presence of triphosphate, the first solid is calcium

BiP is a major ER chaperone and suggested to act as primary sensor in the activation of the unfolded protein response (UPR). How BiP operates as a molecular chaperone and as an ER stress sensor is unknown. Here, by reconstituting components of human UPR, ER stress and BiP chaperone systems, we discover that the interaction of BiP with the luminal domains (LD) of UPR proteins, IRE1 and PERK, switch BiP from its chaperone cycle into an ER stress sensor cycle by preventing the binding of its cochaperones, with loss of ATPase stimulation. Furthermore, misfolded protein-dependent dissociation of BiP from IRE1 is primed by ATP but not ADP. Our data elucidate a previously unidentified mechanistic cycle of BiP function that explains its ability to act as a Hsp70 chaperone and ER stress sensor.

Herein we demonstrate both the importance of Fe(I) in Negishi cross-coupling reactions with arylzinc reagents and the isolation of catalytically competent Fe(I) intermediates. These complexes, [FeX(dpbz)(2)] [X = 4-tolyl (7), Cl (8a), Br (8b); dpbz = 1,2-bis(diphenylphosphino)benzene], were characterized by crystallography and tested for activity in representative reactions. The complexes are low-spin with no significant spin density on the ligands. While complex 8b shows performance consistent with an on-cycle intermediate, it seems that 7 is an off-cycle species.