Muscle cells have an abundant, modified smooth ER called the sarcoplasmic reticulum.

The release and reuptake of Ca2+ by the sarcoplasmic reticulum trigger myofibril contraction and relaxation, respectively

TLS Online TPP Program

#Id: 7966

#Section 3: Genetics, Cellular and Molecular Biology

Binding of BiP to the luminal domain of monomeric Ire1 prevents formation of the Ire1 dimer.

TLS Online TPP Program

#Id: 7965

#Section 3: Genetics, Cellular and Molecular Biology

Unassembled or misfolded proteins in the ER are often transported back to the cytosol, where they are degraded in the ubiquitin-proteasome pathway

TLS Online TPP Program

#Id: 7964

#Section 3: Genetics, Cellular and Molecular Biology

Emphysema caused by a point mutation in -antitrypsin, which is normally secreted by hepatocytes and macrophages.

TLS Online TPP Program

#Id: 7963

#Section 3: Genetics, Cellular and Molecular Biology

A hereditary form of emphysema illustrates the detrimental effects that can result from misfolding of proteins in the ER.

TLS Online TPP Program

#Id: 7962

#Section 3: Genetics, Cellular and Molecular Biology

Hac1 activates transcription of genes encoding several protein-folding catalysts.

TLS Online TPP Program

#Id: 7961

#Section 3: Genetics, Cellular and Molecular Biology

Quantity of free BiP in the ER lumen determines the relative proportions of monomeric and dimeric Ire1.