ATF4

xCT is a sodium independent glutamate transporter that regulates the exchange of extracellular l-cystine and intracellular l-glutamate across the plasma membrane. This process is critical to glutathione production and protection from subsequent oxidative stress.

Mitosis, the process of cell division, involves unique interactions between spindle microtubules and chromosomes, which are regulated by protein structures located on chromosomes known as kinetochores.  CENPF is a kinetochore-associated protein that is localized to chromatin during the G2 and M phases of mitosis.  The main role of CENPF is to secure kinetochore proteins to the correct location surrounding the chromatid and centromere for proper function.

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.

Centromere protein F (CENPF), also named mitosin, is a large human protein of 3113 amino acid residues. Its expression and localization are cell cycle-dependent. The protein levels are low in G1 phase but elevated from S to early M phase. CENPF is a nuclear matrix protein in interphase but is relocated to the kinetochore, the major site of microtubule attachment on chromosome, in M phase (1).