Characterization of cat insulin

Cat insulin was isolated and both chains were characterized by determination of the primary structures. The molecule was found to differ from human insulin at four positions, A8 (Ala), A10 (Val), A18 (His), and B30 (Ala). A comparison with other known insulin structures suggests that cat insulin has an uncommon property: it appears to be the only insulin found so far with His at position A18. The difference is compatible with a conserved overall conformation but this histidine occupies a position close to the suggested receptor interacting area and may influence some binding properties.