The insulin receptor is a protein found on the surface of certain cells, such as muscle and fat cells. It plays an important role in regulating blood sugar levels by allowing glucose to enter these cells when needed. When insulin (a hormone produced by the pancreas) binds to the insulin receptor, it triggers a series of events that ultimately leads to the uptake and storage of glucose within the cell. This helps to lower blood sugar levels back towards normal. The insulin receptor is therefore an essential component in maintaining proper glucose homeostasis in the body.