proinsulin

biochemistry

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In hormone: Insulin
…cell as the single-chain compound proinsulin, which is disrupted by an enzyme-catalyzed reaction to form the two chains of the active hormone. As with other polypeptide hormones, extensive variation in amino acid composition of the molecule occurs among different species, with the differences tending to be greater between the more…
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In insulin
…a 74-amino-acid prohormone molecule called proinsulin. Proinsulin is relatively inactive, and under normal conditions only a small amount of it is secreted. In the endoplasmic reticulum of beta cells the proinsulin molecule is cleaved in two places, yielding the A and B chains of insulin and an intervening, biologically inactive…
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