Pre-proinsulin

Fig. 7.1. The formation of insulin and glucagon from their respective precursors, pre-proinsulin and pre-proglucagon in domestic fowl.

Pre-proprotein a precursor in the biosynthesis of a secretory protein (see Signal hypothesis). The P-p. possesses an Af-terminal signal peptide sequence in addition to the proprotein sequence, e.g. pre-proinsulin, pre-protrypsin, pre-proparathormone, pre-pro-mellitin, etc. 

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