Glucose transporter type 2 (GLUT2 or SLC2A2) is a facilitative glucose transporter. This isoform likely mediates the bidirectional transfer of glucose across the plasma membrane of hepatocytes and is responsible for uptake of glucose by the beta cells. GLUT2 is also part of the glucose-sensing mechanism of the beta cell and participate with the Na+/glucose cotransporter in the transcellular transport of glucose in the small intestine and kidney. Defects in GLUT2 are the cause of Fanconi-Bickel syndrome, characterized by hepatorenal glycogen accumulation, proximal renal tubular dysfunction, and impaired utilization of glucose and galactose.
MDM2 mediates ubiquitination of p53/TP53, leading to its degration by the proteasome. MDM2 inhibits p53/TP53- and p73/TP73-mediated cell cycle arrest and apoptosis by binding to their respective transcriptional activation domains. MDM2 also acts as an ubiquitin ligase towards itself and ARRB1, permits the nuclear export of TP53/p53, and promotes proteasome-dependent ubiquitin-independent degradation of retinoblastoma RB1 protein.
Katacalcin is a potent plasma calcium lowering peptide. Katacalcin belongs to the calcitonin family, that causes a rapid but short-lived drop in the level of calcium and phosphate in blood by promoting the incorporation of these ions in the bones. Calcitonin is cleaved into 2 chains, calcitonin and katacalcin.