Structurally, all these peptides consist of two polypeptide chains (A and B)
linked by two disulfide bonds.
B chain xxxxxxCxxxxxxxxxxxxCxxxxxxxxx
| |
A chain xxxxxCCxxxCxxxxxxxxCx
***************
| |
+----+
'C': conserved cysteine involved in a disulfide bond.
'*': position of the pattern.
As shown in the schematic representation above, they all share a conserved
arrangement of four cysteines in their A chain. The first of these cysteines
is linked by a disulfide bond to the third one and the second and fourth
cysteines are linked by interchain disulfide bonds to cysteines in the B
chain. As a pattern for this family of proteins, we have used the region
which includes the four conserved cysteines in the A chain.
New insulin-like proteins with atypical disulfide bond pattern characterized in Caenorhabditis elegans by comparative sequence analysis and homology modeling.
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