True statement regarding insulin:
Produced by alpha cells of pancreas
Two polypeptide chains are bound by disulfide linkages
Shifts potassium outside the cell
S.c insulin tl/2 is 60 mins
Ref: Harper's Illustrated Biochemistry,28th editionExplanation:InsulinSecreted from pancreatic islet b cellsReleased regulated by blood (glycemic thresholdSynthesized as a single chain : pro-insulinInsulin is formed from proinsulin (removal of the connecting or "C" peptide)Insulin is thus made up of 2 chainsA (21 amino acids) and B (30 amino acids)Connected to each other by 2 inter disulfide bridges and 1 intra disulfide bridgeAll necessary for its hormone activity.ActionsStimulates glucose oxidation & storage and inhibits glucose productionStimulates glycogen synthaseInhibits phosph orylaseInhibits gluconeogenesisStimulates glucose transport into adipocytes, which is then converted intoTGInhibits hormone-sensitive lipase (HPL) (|cAMP) and lipoprotein lipaseActivates GLUT1Stimulates fatty acid and triglyceride synthesisInhibits I i poly sis and proteolysisShifts potassium ions from ECF to ICF
Chemistry of Carbohydrates, Amino sugars, and Mucopolysaccharides