[1][2] 1094568137ENSG00000105438ENSMUSG00000002778P24390Q99JH8NM_006801NM_133950NP_006792NP_598711Retention of resident soluble proteins in the lumen of the endoplasmic reticulum (ER) is achieved in both yeast and animal cells by their continual retrieval from the cis-Golgi or a pre-Golgi compartment.

Sorting of these proteins is dependent on a C-terminal tetrapeptide signal, usually lys-asp-glu-leu (KDEL) in animal cells and his-asp-glu-leu (HDEL) in S. cerevisiae.

[8] In vitro studies in yeast have revealed that this receptor regulates membrane transport in the early stages of the secretory pathway from ER to the Golgi.

[7] Upon analysis, it was found that KDEL mutant mice had proliferation in their sarcoplasmic reticulum (SR) and a narrowing in the transverse tubule compared to the wild-type and controls.

L-type channels expression was lower in the plasma membrane of the KDEL D193N heart cells due to the narrowing of transverse tubules.

[7] The researchers concluded that hyperubiquitination and saturation of the proteasome system results due to the accumulation of misfolded protein, which induces stress.

CHOP is a transcription factor that is elevated during ER stress and causes apoptosis of cells during the process of an unfolded protein response.