Isolation and primary structure of VIP from sheep brain.

The amino acid sequence of the vasoactive intestinal polypeptide (VIP) is well conserved between species. Thus, all mammalian VIPs isolated so far, except that of the guinea pig, have the same amino acid sequence. This study describes the isolation and primary structure of sheep brain VIP. The purification was followed with a bioassay and a VIP receptor assay. The amino acid sequence of the isolated sheep VIP is identical to that of the pig, human, ox, rat, rabbit, goat and dog VIP.