The endoplasmic reticulum (ER) is a vital cell organelle involved in diverse cellular processes that include protein synthesis, protein folding, and lipid metabolism. ER proteins, which reside within or interact with the ER, play essential roles in maintaining ER function and facilitating cell signalling pathways. Resident ER proteins typically possess specific targeting signals that direct their localization to the ER. The most common signal is the ER signal sequence, a hydrophobic stretch of amino acids at the N-terminus of the protein. This signal is recognized by the signal recognition particle (SRP), which facilitates the protein's co-translational translocation into the ER. ER proteins contribute to the proper folding and quality control of newly synthesized proteins. Chaperones, such as BiP/Grp78, assist in the folding process, whilst ER-associated degradation (ERAD) machinery ensures the disposal of any misfolded proteins. The unfolded protein response (UPR) can also be activated when the ER protein folding capacity is overwhelmed, leading to the upregulation of chaperones and ERAD components. ER proteins are involved in many protein post-translational modifications, including glycosylation, disulfide bond formation, and lipidation. These modifications are often crucial for protein stability, activity, and proper trafficking within the cell. For example, the ER-resident enzyme glucosyltransferase is responsible for protein glycosylation, a process important for protein folding and recognition. In addition to protein processing, the ER also acts as a major intracellular calcium store, and ER proteins play crucial roles in regulating calcium homeostasis and signalling. Calcium-release channels, such as inositol trisphosphate receptors (IP3Rs), located on the ER membrane, release calcium into the cytoplasm upon activation by IP3. Conversely, sarco/endoplasmic reticulum calcium ATPases (SERCAs) actively transport calcium ions from the cytoplasm into the ER lumen. The unfolded protein response (UPR) is a stress response pathway activated upon ER protein folding stress. ER proteins, such as IRE1, PERK, and ATF6, sense unfolded proteins and initiate a series of signalling events to restore ER homeostasis. The UPR can modulate cell fate decisions, including cell survival or apoptosis, depending on the severity and duration of the stress. Finally, ER proteins participate in lipid metabolism and lipid-mediated signalling processes. Lipid synthesis enzymes, such as sterol regulatory element-binding proteins (SREBPs), are ER-associated proteins that regulate cholesterol and fatty acid biosynthesis. These lipids serve as important signalling molecules involved in cellular processes, including transcriptional regulation and inflammation. We provide a comprehensive product range of research reagents for studying ER proteins, including GRP94 antibodies, ARF1 antibodies, VCP antibodies, LRAT antibodies, and Cyclophilin B ELISA Kits. Explore our full ER proteins product range below and discover more, for less.