insulin protein

Function

• hormone secreted by the islets of Langerhans in the pancreas
• regulates carbohydrate & fat metabolism
• induces hepatocytes & myocytes to internalize glucose from plasma & store it as glycogen in the liver & muscle, respectively
• induces translocation of GLUT-4 glucose transporter to the plasma membrane in skeletal muscle & adipocytes resulting in intracellular influx of glucose
• inhibits release of glucagon
• increases K+ uptake by skeletal muscle cells possibly via translocation of the Na+/K+-ATPase to the plasma membrane
• inhibits lipolysis, gluconeogenesis, autphagy
• able to cross the blood-brain barrier

Structure

• heterodimer linked by 2 disulfide bonds
• a common precursor, proinsulin, gives rise to both insulin subunits & C-peptide
• apparently stored as a hexamer chelated by Zn+2 for stability

Pathology

• deficiency results in diabetes mellitus type 1
• insulin resistance or down-regulation of insulin receptors results in diabetes mellitus type 2
• insulinomas are islet cell tumors secreting insulin

More general terms

• secreted peptide
• pancreatic hormone
• peptide precursor
• multisubunit protein

More specific terms

• C-peptide
• insulin, isoform 2; INS-IGF2 readthrough transcript protein (INS-IGF2)
• proinsulin

Additional terms

• anti-insulin antibody
• insulin analog (synthetic insulins, recombinant insulins)
• insulin device (device for administering insulin)
• insulin for injection (Novolin, Humulin, Lente, Semilente, Ultralente, Iletin, NPH (isophane), PZI, INS)
• insulin in serum
• insulin receptor antagonist (insulin antagonist)
• insulin receptor; IR; (INSR)
• insulin resistance

Database

• OMIM: https://mirror.omim.org/entry/176730
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=3630
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=196300
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3082397