SSR2 Human

Signal Sequence Receptor, Beta (SSR2), also known as Translocon-associated protein beta (TRAPB), is a crucial component of the translocon complex in the endoplasmic reticulum (ER) membrane. This protein plays a significant role in the translocation of nascent polypeptides across the ER membrane, ensuring proper protein folding and processing.

The Signal Sequence Receptor, Beta is a type I membrane protein that is part of a larger complex known as the signal sequence receptor (SSR) complex. This complex is composed of four subunits: alpha, beta, gamma, and delta. The beta subunit, specifically, is characterized by its single transmembrane domain and a large luminal domain. The human recombinant form of SSR2 is produced using recombinant DNA technology, which involves the insertion of the SSR2 gene into an expression vector, followed by its expression in a suitable host system, such as E. coli or CHO cells.

The primary function of SSR2 is to facilitate the translocation of newly synthesized proteins into the ER lumen. This process is essential for the proper folding, modification, and assembly of proteins. SSR2 interacts with the signal recognition particle (SRP) and the SRP receptor, guiding the ribosome-nascent chain complex to the translocon. Once the complex is positioned at the translocon, SSR2 helps in the insertion of the nascent polypeptide into the ER membrane, where it can undergo further processing.

SSR2 is ubiquitously expressed in various tissues, reflecting its fundamental role in protein synthesis and processing. High levels of SSR2 expression are observed in tissues with a high rate of protein synthesis, such as the liver, pancreas, and secretory glands. This widespread expression pattern underscores the importance of SSR2 in maintaining cellular homeostasis and function.

The expression and activity of SSR2 are tightly regulated at multiple levels. Transcriptional regulation of the SSR2 gene is influenced by various transcription factors and signaling pathways that respond to cellular stress and demand for protein synthesis. Post-translational modifications, such as phosphorylation and glycosylation, also play a role in modulating the stability and function of SSR2. Additionally, the interaction of SSR2 with other components of the translocon complex and chaperone proteins ensures its proper function and integration into the ER membrane.

Mutations or dysregulation of SSR2 have been implicated in various diseases, including neurodegenerative disorders and cancer. Defects in the translocation process can lead to the accumulation of misfolded proteins, triggering ER stress and the unfolded protein response (UPR). Chronic ER stress is associated with the development of conditions such as Alzheimer’s disease, Parkinson’s disease, and certain types of cancer. Understanding the role of SSR2 in these processes can provide insights into potential therapeutic targets for these diseases.