Antibody database

Calreticulin is a calcium-dependent ER chaperone, involved in protein folding, maturation, and cellular localization. Calreticulin is a highly conserved 48 kDa protein encoded by the CALR gene. Calreticulin and its homolog calnexin regulate the folding and degradation of newly synthesized glycoproteins as they are translocated into the ER (1). Misfolded proteins recognized by calreticulin are targeted to the ER-associated degradation (ERAD) pathway. Within the ER, calreticulin also plays an important role in calcium homeostasis.

The 78 kDa glucose-regulated protein (GRP78) is the eukaryotic orthologue to the prokaryotic heat shock 70 kDa protein 5 (HSPA5). GRP78 is also sometimes referred to as BiP. GRP78 is a member of the HSP70 family and plays dynamic roles in protein regulation within the endoplasmic reticulum. GRP78 is the most abundant chaperone in the ER and plays an important role in regulating the unfolded protein response (UPR) (1). GRP78 forms a multiprotein chaperone complex with DNAJB11, HSP90B1, HYOU, PDIA2, PDIA4, PDIA6, PPIB, SDF2L1, UGT1A1, and ERP29.

The mammalian forkhead O class transcription factors (FOXO) regulate diverse cellular processes such as metabolism, cell cycle, and apoptosis. Activity of these transcription factors can be regulated by diverse post-translational modifications including phosphorylation, acetylation, and ubiquitination (1). These modifications can alter nuclear transport, DNA binding, and protein-protein interactions to alter transcriptional activity. The best studied member of the FOXO family is FOXO1.

Caspase-2 is a highly conserved member of the caspase family involved in the initiation and execution of apoptosis. While its function is still poorly understood, caspase-2 is thought to be important for apoptosis in response to DNA damage, bacterial infection, or abnormal mitosis (1). Caspase-2 contains an N-terminal caspase recruitment domain, the large p19 subunit containing the active site, and the small C-terminal p12 subunit (1). In response to various apoptotic signals caspase-2 undergoes dimerization.

The structure and organization of the plasma membrane is maintained by an underlying network of cytoskeletal proteins including actin and spectrin. Adducin, a member of this protein network, binds to bundles and caps actin filaments and links them to spectrin. Adducin’s role in organizing the cytoskeletal meshwork at the plasma membrane is important in signal transduction, cell-cell adhesion, and cell migration (1).

CD63 is a type II membrane protein belonging to tetraspanin superfamily and it play key roles in the activation of several cellular signaling cascades along with acting as TIMP1 receptor. It is expressed by activated platelets, monocytes, macrophages, granulocytes, T /B cells, and different type of cancer cells. CD63 localizes to endosomes, lysosomes and on the cellular surfaces, and is often considered as a marker for late endosomes as well as for lysosomes.

Ki-67/MKI67 is an antigen which is expressed during G1, S, G2, and M phases of the cell cycle (mitotically active cells), but not during G0 phase (resting cells). It is a large protein with expected molecular weight of about 395 kDa, and it has a very complex localization pattern within the nucleus, one which changes during cell cycle progression. During interphase, Ki-67 antigen can be exclusively detected in the nucleus, whereas in mitotic phase, most of Ki67 pool gets relocated to the chromosomal surface.

Ataxia telangiectasia mutated (ATM) is essential for the maintenance of genomic stability. ATM is a 370 kDa serine-threonine kinase that is constitutively expressed in various tissues. Although primarily nuclear, ATM is also found at lower levels associated with cytoplasmic vesicles. As a PI 3-kinase family member, ATM is able to phosphorylate a wide variety of substrates including proteins involved in sensing and repairing DNA damage such as p53 and Brca1 (2). Normally ATM is found as an inactive homodimer.

Caspase-1 is an enzyme involved in the conversion of interleukin-1 into its active secreted form. Interleukin-1 mediates inflammatory responses during infection and disease. Caspase-1 is recruited to and activated by the inflammasome complex (1). Under normal cellular conditions caspase-1 exists in an inactive pro form. Following stimulation with LPS or various microbial signals procaspase-1 is proteolytically cleaved into 10- and 20-kDa subunits that are enzymatically active (2).

Eukaryotic initiation factor 2 (eIF2) regulates global protein translation by binding to Met-tRNA and the 40S ribosome to form the pre-initiation complex. eIF2 is a heterotrimer consisting of alpha, beta, and gamma subunits. The 36kDA eIF2α subunit serves a key regulatory role. Phosphorylation of the serine residue at position 51 is able to block the formation of the pre-initiation complex and halt global protein translation. This regulatory mechanism allows cells to respond and adapt to diverse stresses such as nutrient deficiencies, viral infection, or general ER-stress.