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Lecture

Regulation of the Endoplasmic Reticulum BiP

Description

This lecture covers the regulation of the Endoplasmic Reticulum (ER) chaperone BiP, including its role in protein folding, quality control, and the Unfolded Protein Response (UPR). It explores the impact of high Ca²+ levels on BiP function, the formation of BiP oligomers, and the reversible covalent modification of BiP. The lecture also discusses the interaction between BiP and its substrates, the influence of Ca²+ on BiP's ATPase cycle, and the selective responsiveness of ER-localized Hsp70s to Ca²+. Additionally, it examines how ER Ca²+ depletion affects BiP-substrate interactions and UPR activation. The presentation concludes with alternative models for UPR activation by ER Ca²+ depletion and the implications of Ca²+ on BiP's chaperone cycle.

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Related concepts (28)

Chaperone (protein)

In molecular biology, molecular chaperones are proteins that assist the conformational folding or unfolding of large proteins or macromolecular protein complexes. There are a number of classes of molecular chaperones, all of which function to assist large proteins in proper protein folding during or after synthesis, and after partial denaturation. Chaperones are also involved in the translocation of proteins for proteolysis. The first molecular chaperones discovered were a type of assembly chaperones which assist in the assembly of nucleosomes from folded histones and DNA.

Endoplasmic reticulum

The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum (RER), and smooth endoplasmic reticulum (SER). The endoplasmic reticulum is found in most eukaryotic cells and forms an interconnected network of flattened, membrane-enclosed sacs known as cisternae (in the RER), and tubular structures in the SER.

Protein folding

Protein folding is the physical process where a protein chain is translated into its native three-dimensional structure, typically a "folded" conformation, by which the protein becomes biologically functional. Via an expeditious and reproducible process, a polypeptide folds into its characteristic three-dimensional structure from a random coil. Each protein exists first as an unfolded polypeptide or random coil after being translated from a sequence of mRNA into a linear chain of amino acids.

Protein biosynthesis

Protein biosynthesis (or protein synthesis) is a core biological process, occurring inside cells, balancing the loss of cellular proteins (via degradation or export) through the production of new proteins. Proteins perform a number of critical functions as enzymes, structural proteins or hormones. Protein synthesis is a very similar process for both prokaryotes and eukaryotes but there are some distinct differences. Protein synthesis can be divided broadly into two phases—transcription and translation.

Heat shock protein

Heat shock proteins (HSP) are a family of proteins produced by cells in response to exposure to stressful conditions. They were first described in relation to heat shock, but are now known to also be expressed during other stresses including exposure to cold, UV light and during wound healing or tissue remodeling. Many members of this group perform chaperone functions by stabilizing new proteins to ensure correct folding or by helping to refold proteins that were damaged by the cell stress.

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