Insulin is released by the beta islets of the pancreas after a meal when glucose levels are high. Released as a peptide, insulin
binds to a unique class of receptors that lead to the reduction of blood sugar levels. The insulin receptor has a tyrosine kinase intracellular domain. However, unlike many other similar single transmembrane receptors with a tyrosine kinase activity (such as growth factor receptors), the insulin receptor is a cross linked dimer in the resting state made of two alpha and two beta strands (heterotetramer). Which of the following statements describe how the insulin receptor is activated? Choose one or more: Following insulin binding, the receptor will bind with another receptor as long as only one insulin peptide is bound. This is an example of a negative feedback cooperative regulation. The intracellular domain of the insulin receptor, specifically the tyrosine's, must be phosphorylated to recruit the intracellular signaling partners. An insulin receptor has two binding sites for insulin, and each ligand is required to begin autophosphorylation. Insulin binding to the insulin receptor induces a conformational change that stimulates tyrosine autophosphorylation of the beta subunits.
The correct answers are the second and the last statement.
Explanation:
Insulin refers to a hormone produced in the body that assists in monitoring the procedure of delivering glucose and storing it. The discharging of insulin takes place by the beta islets found in the pancreas. The discharging of insulin takes place when the level of glucose in the bloodstream increases. At that time, insulin assists in uptaking glucose for its metabolism and also in its storing.
The insulin exhibits a transmembrane receptor that comprises a tyrosine kinases intracellular domain. The insulin combines with its receptor at its external edge and results in a variation in its conformation, which stimulates two tyrosine kinases. The tyrosine kinase refers to a dynamic part of the receptor that moves around.
The stimulation takes place because of the phosphorylation of the tyrosine kinases that then phosphorylates other proteins like intracellular signaling partners. This stimulation of tyrosine makes a path for the combination of ATP with the active site.
The correct answer is d. morula. <span> A morula is a stage in early development, formed 3–4 days after fertilization. It is a 16-cell mass which forms a solid ball contained within the zona pellucida. A morula develops into a blastocyst.</span>
