Purified anti-human CD220

CD220, also known as insulin receptor, is a type I transmembrane receptor tyrosine kinase composed of two extracellular alpha-subunits and two transmembrane beta-subunits. Binding insulin, the insulin receptor forms a heterotetramer of two units to induce autophosphorylation and activation of the tyrosine kinase activity of the receptor. Activation of insulin receptor leads to subsequent downstream signaling in metabolic regulation, inducing glucose uptake, cell growth, differentiation, and apoptosis. Gene mutation in the insulin receptor or decreased insulin receptor signaling leads to insulin-resistant diabetes mellitus and noninsulin-dependent diabetes mellitus (diabetes mellitus type 2). Most normal cells constitutively express insulin receptors. In hematopoietic cells, insulin receptor is constitutively expressed on monocytes and selectively expressed on activated lymphocytes.