the presence of a cooh-terminal extension to the b-chain is consistent with the occurrence of a single base mutation in the region of the gene encoding one of the dibasic residue processing sites [ arg31 ( aga ) -- -- ile* ( aua ) ] with the result that the ratfish has utilised an alternative cleavage site within the c-peptide region of proinsulin .
C0006558
c-peptide
C0033362
proinsulin