Sandbox Reserved 1627: Difference between revisions

The insulin receptor is a [http://en.wikipedia.org/wiki/Dimer_(chemistry) dimer] of heterodimers made of two <scene name='83/832953/Alpha_subunits/4'>alpha subunits</scene> and two <scene name='83/832953/Beta_subunits/3'>beta subunits</scene> <ref name="Tatulian">PMID:26322622</ref>. Within the extracellular ectodomain, there are four potential <scene name='83/832953/Binding_sites/3'>binding sites</scene> that can interact with insulin ligands on the extracellular side of the membrane. The insulin receptor has only been imaged in pieces, which has led to proposed structures of the entirety of the receptor based on the function of downstream tyrosine autophosphorylation.[http://www.rcsb.org/structure/1IR3 PDB 1IR3]

The conformation change from the inactive to active state upon insulin binding has a [http://en.wikipedia.org/wiki/Time_constant time constant] of six minutes. <ref name= "Tatulian" /> [http://en.wikipedia.org/wiki/Autophosphorylation Autophosphorylation] of the beta subunits reaches a maximal level in about one minute, and lasts for approximately six to ten minutes. One insulin receptor substrate has a [http://en.wikipedia.org/wiki/Half-life half-life] of 3.5 minutes where it is able to be phosphorylated by the tyrosine kinases of the beta subunit and then act as a central hub for further downstream signaling pathways. Once insulin binds to the alpha subunit, the receptor remains active for approximately ten minutes before the insulin is degraded and the receptor returns to its inactive conformation. This time frame puts a perspective on how long it takes for the human body to store excess glucose in their blood stream from a recent meal as glycogen for later use as fuel. <ref name="Tatulian" />