I am researching diabetes. I know the b cells in the Islets of Langerhans make insulin from proinsulin. From what is proinsulin made? Is it from glucogen? Is it made in the colon, in all muscle cells, in the b cells? Is it ever present in the blood or only made in response to a meal? Does anything store proinsulin? -- Thanks
**edited by moderator**no emails allowed**
**edited by moderator**no emails allowed**
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Here's another answer that the original poster will probably never see. Oh well, I wasn't around here when the original question was posted!! :-)
Proinsulin is the prohormone precursor to insulin made in the beta cell of the islets of Langerhans. In humans, proinsulin is encoded by the INS gene. (INS is the gene symbol for insulin).
Proinsulin is synthesized in the endoplasmic reticulum, where it is folded and its disulfide bonds are oxidized. It is then transported to the Golgi apparatus where it is packaged into secretory vesicles, and where it is processed by a series of proteases to form mature insulin. Mature insulin has 39 fewer amino acids; 4 are removed altogether, and the remaining 35 form the C-peptide. The C-peptide is abstracted from the center of the proinsulin sequence; the two other ends (the B chain and A chain) remain connected by disulfide bonds.
Proinsulin is the prohormone precursor to insulin made in the beta cell of the islets of Langerhans. In humans, proinsulin is encoded by the INS gene. (INS is the gene symbol for insulin).
Proinsulin is synthesized in the endoplasmic reticulum, where it is folded and its disulfide bonds are oxidized. It is then transported to the Golgi apparatus where it is packaged into secretory vesicles, and where it is processed by a series of proteases to form mature insulin. Mature insulin has 39 fewer amino acids; 4 are removed altogether, and the remaining 35 form the C-peptide. The C-peptide is abstracted from the center of the proinsulin sequence; the two other ends (the B chain and A chain) remain connected by disulfide bonds.
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