INSR(INSULIN RECEPTOR) is a tetramer of 2 alpha and 2 beta subunits that are coded by a single gene and are joined by disulfide bonds, a mechanism parallel to that of its ligand, insulin. It belongs to the large class of tyrosine kinase receptors. The insulin receptor gene is mapped to 19p13.2. The insulin receptor mediates their activity by causing the addition of a phosphate group to particular tyrosines on certain proteins within a cell. The INSR gene spans more than 120 kb and has 22 exons. Functional studies of the INSR SNPs show no effect on mRNA levels or splicing in peripheral blood leukocytes or on binding of insulin to mononuclear cells.